Ironically, before he shot and killed Abraham Lincoln at Ford’s Theatr

"before" sounds like the immediate period before; whereas 'prior to' sounds like some other occasion.

Please explain

philipssonicare , I am not sure exactly what you are asking, but I will try to answer.

No, "prior to" does not connote some other occasion.
The phrase is used commonly and incorrectly to mean "before."

If we need to indicate that something happened before something else in time, use before, not prior to.

Prior is an adjective that means earlier, previous, or preceding.
That adjective should come before nouns, this way:
He could not attend the wedding because he had a prior engagement.
My lease requires the landlord to give me two weeks' prior notice if the landlord does not want to renew the lease.

Using "prior to" as a prepositional phrase is weird and wrong, albeit common.

We do not say "earlier to."
We do not say "preceding to."
We should not say "prior to."

In the context of time, before is correct and prior to almost never is.
(I can't think of an example in which "prior to" is correct.)

Lawyer, cross-examining a witness: Prior to that date, on which you did X, Y, and Z. . .
Lawyer, cross-examining a witness: Earlier to that date, on which you did X, Y, and Z. . .
Lawyer, cross-examining a witness: Before that date, on which you did X, Y, and Z . . .

Hope that helps.

Split #1: Prior to vs. before

If we need to convey "during the time that preceded event X in time," we use before.

Prior is an adjective that means earlier, preceding, previous.
We do not say earlier to or preceding to. Nor should we say prior to.

The sentence structure is more effective as-is, but the error is easier to see if I rearrange the sentence a bit.

John Wilkes Booth had performed in front of Abraham Lincoln before Booth shot and killed Lincoln.
D, rearranged) John Wilkes Booth had performed in front of Abraham Lincoln earlier to when Booth shot and killed Lincoln.
E, rearranged) John Wilkes Booth had performed in front of Abraham Lincoln earlier to the shooting and killing of Lincoln.
Options D and E incorrectly use prior to rather than before.

Eliminate D and E

Split #2: Verb tense
The usage of past perfect requires that there be at least one instance of simple past.

Option C uses two past perfect tenses [had/have + past participle]: had shot and killed, and had performed
That usage removes the simple past tense needed in order to create a correct construction with "had performed" in the non-underlined portion.

Eliminate C

Split #3: Changed meaning or Epically Poor Construction or Whodunnit

In option B, anyone could have been responsible for "the shooting and killing of" Lincoln.
In that case, the meaning of the sentence changes.
The "ironically" part is lost.
If Booth did not do the shooting and killing of Lincoln, nothing about Booth's having performed at the theater where Lincoln was assassinated is ironic.

Eliminate B

Option A: Ironically, before he shot and killed Abraham Lincoln at Ford’s Theatre, John Wilkes Booth had performed in front of the president in the very same venue.
Ironically: look for contrast

before he shot and killed A. Lincoln at Ford's Theatre: subordinate clause, before is a subordinating conjunction
-- he is the subject of the subordinate clause, and the antecedent is the subject J.W. Booth
-- shot and killed = compound verb correctly in simple past tense

John Wilkes Booth had performed . . .: subject + past perfect verb that accords with the timeline
(irony: Lincoln's assassin had entertained Lincoln at the very same theater)

The correct answer is A.

generis
'prior to' is a phrase in the OED. I know GMAC are seemingly stricter than the dictionary, but they have used 'prior to' on many occasions. This is merely the first few GMAC-sourced links from the GMATClub search

https://gmatclub.com/forum/prior-to-196 ... 32112.html
https://gmatclub.com/forum/prior-to-197 ... 03048.html
https://gmatclub.com/forum/wolves-gener ... 33936.html
https://gmatclub.com/forum/the-greatest ... 97171.html
https://gmatclub.com/forum/many-politic ... 37377.html

Do you have a source for 'prior to' being rejected by GMAC?

philipssonicare - wow, I wish your original question had been a little clearer.
I could have saved you a lot of time and said, "I do not recall having seen a single question whose correct answer turned on the distinction between prior to and before.
Then again, I would never say never.
If the issue were to be tested I would follow what I think is the weight of authority.
I would use before."

(Before all else: How, exactly, do you plan to eliminate Answer D?)

Your research does not prove what you want it to prove, but that's okay.
This issue is much too small to give this kind of treatment, but it demonstrates what I think
may be a better process.

Below I cite to grammarians and display three sentence errors in RC and one in CR,
all four of which I found in 8 minutes. (I even failed to mention other errors.)
RCs and CRs are not reliable for SC.

And no, I do not have a source in which "prior to" was rejected by GMAT writers, because
I do not have a question that tests the issue. I am 99% sure that such a question does not exist.

I have read well over 700 official questions many times,
and because this issue irks me (as do split infinitives and the word "this" without a referent),
I'm confident that I would recall having seen the issue. I am not 100% certain, but I am confident.

From the way that you punctuate and from your syntax, I suspect that you are
a native or very fluent speaker of British English. In British English, "prior to" is common---not necessarily correct, but common.

I suspect that no one will ever see the issue tested.
Whoever wrote this Veritas question, though, seems to have been testing the issue.
If not, then we have two correct answers, A and D.

Take a look at my citations and research below.

Your research -
• RC and CR are just okay as prep materials for SC.
RC tends to have too many errors. CR has errors. I demonstrate that part below.
If you are convinced by your research, read no further.

• One example of material used in a non-underlined portion of one SC question does not sway me one way or the other.
-- I have seen four or five errors in non-underlined portions. I am not inclined to go hunting at the moment.
-- Do a little bit of research. You will find that GMAT makes errors in SC in non-underlined portions.

• My position is
-- that no one knows what GMAC's approach is;
-- that GMAC probably is not going to test the issue; and
-- that the people who wrote sentences with errors in official materials on this issue probably didn't know better.

• Finally if GMAT were to test the issue, I'd approach it exactly as I did in this question.
I would be following a number of grammarians, just a few of whom are listed below.

Specifically on the GMAT, mikemcgarry , writing HERE
suspects that the GMAT folks would not like the constructions that I rejected in answers D and E of this question.
In Good Usage v. Common Usage in The Chicago Manual of Style HERE
Former editor of the New York Times Book Review and an author of five books on the English language, Patricia O'Conner writes on the grammarphobia blog HERE that
In the Columbia Journalism Review, Evan Jenkins writes, HERE:
David Foster Wallace, a grammarians' writer if ever there were one, wrote, HERE
As a professional editor of many different kinds of prose, I follow the same rule that the above-listed and other grammarians do.
I am absolutely on the stricter side of the grammar spectrum.

• I would recommend that you not use GMAT RC passages or CR questions as sources for Sentence Correction.
The standards for SC are tough.
To study for SC, I would review the 700+ official questions that exist.
I would not read RC and CR materials.

mikemcgarry writes here, for example in GMAT Club post:
GMAT RC usually adheres to GMAT SC standards---but not always. I have seen examples, in GMAT RC passages, that run afoul of the high standards set by the GMAT SC. Again, this will be usually helpful, but not perfect.

• RC errors? It took me five minutes to find three errors in two RC passages in OG 2018, and another three minutes to find an error in CR.

RC errors that I found:
-- This is not generally true in the case of skilled activities such as electrical work, where, consequently, a guarantee might have greater customer appeal. (OG 2018, page 366)
-- It is true that as the capacity of a manufacturing operation rises, costs per unit of output fall as plant size approaches "minimum efficient scale," where the cost per unit of out put reaches a minimum, determined roughly by the state of existing technology and size of the potential market. (OG 2018, page 388)

-- Dicey: Staff members would know what service standards are expected of them and also know that the success of the business relies on their adhering to those standards.

• Errors in CR - It took me three minutes to find an error in CR. Same book.
Analysis of the carved picture frame, which has been identified as the painting's original seventeenth-century frame, showed that it is made of wood found widely in northern Germany at the time, but rare in the part of France where Birelle lived.

The wood was found rare? As if it were a steak?

The disparity between what is expected in SC and what GMAC delivers in RC and CR has been noted frequently.

My point is not to disparage people who work hard to write these passages and CR questions, but rather to demonstrate that a fixation on perfection is not likely to serve its purpose.

I don't see the point in keeping an error sheet, but given this level of microscopic analysis, perhaps I should do so.

• I would also recommend that you be careful with OED.

The OED asserts that like means "for example" and "such as" HERE.
Writers of the OED used this example: "the cautionary vision of works like Animal Farm and 1984."
I recommend that when you take the GMAT you ignore what the OED has to say about that matter.
SC #131 in OG 2016 tests like vs. such as

• official position?

You saw Mike McGarry's position.
I doubt that the issue will be tested. I will not spend any more time on the issue, though, and I hope you do not, either.

If GMAT were to test the issue, and I were given the choices above, I would reject D and E.

• So let's toss out the highlighted citations to RC passages and one CR question.

We are left with one official SC question in which, in the non-underlined portion, you found the words "prior to."
I'm not persuaded.
So my answer is that as far as I know, GMAC has not made this issue an issue.
Veritas and Mike McGarry seem to think that the GMAC might do so.

That's the most we can conclude, I think.

generis

Thank you for a very comprehensive post. I actually didn't plan to eliminate D, I chose it as the correct answer and was wrong.
I am seeking understanding, not to prove any provider or moderator wrong. If I were an expert I would be answering, not asking, questions.

RC tends to have too many errors. CR has errors
I have seen four or five errors in non-underlined portions. I am not inclined to go hunting at the moment

I did not know the above, hence I posted a few links of GMAC writing something different.

As you guessed, I am a native speaker of British English. Prior to Before studying for the GMAT, I had not heard any grammatical terms outside the broad 'noun, verb, adjective, adverb'.

Again, thanks for a very comprehensive post. I can only pray that every question I ever ask gets such thorough treatment. Kudos!

Two actions happened in the past and so we need simple past for action-2 and past perfect for action-1

action-1: performed (..)
action-2: shot and killed (..)

action-1 is already using past perfect ( John had performed.. )
action-2 needs to be simple past. Option A is using the same.

philipssonicare , I answered your question because it was a good opportunity to highlight a few items that arise frequently and that do not get a lot of attention.

1) people trained in British English (B.E.) need to be aware that a few GMAC rules are not typical of B.E.

-- ironically, the Oxford comma. And everyone should know that newspapers around the world rarely use the Oxford comma. In journalism every space counts.

-- which and that are used interchangeably in B.E. Not so in the U.S., and not so on the GMAT

-- simple past and present perfect.
In the U.S., we can say, "I signed the wrong document. Would you help me fix the mistake?"
In B.E., people usually say, "I've signed the wrong document. Would you help me fix the mistake?"
In B.E., if an event happened recently and affects the present, present perfect is common ("I have signed" or "I've signed").
The U.S. way sounds incorrect to B.E. speakers

2) After a person learns the major rules, one of the best ways to supplement how the rules are tested is to review official questions. Patterns emerge.

3) philipssonicare , I hear you about the grammar part. (Not much grammar is taught in the United States either. I blame postmodern obscurantists.

Your strikethrough is funny.

Then again, so is your username.

anvesh004 , okay, how do you plan to eliminate option D?

It, too, uses simple past.

Yeah. I should have mentioned that.

IMO, prior to when is unidiomatic.

Prior to is for sequence of actions and when is used for action happened at the same instant. So, those 2 can't be put together.

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