OFFICIAL EXPLANATIONProject SC Butler: Sentence Correction (SC1)
Quote:
The theory of plate tectonics, which was first proposed in the early 1960s as an answer to the problems with the theory of continental drift, positing that earth’s landmasses sit atop massive plates, which shift with the passage of time.
The sentence indicates that the theory of plate tectonics posits or claims something.
THE OPTIONSQuote:
A) tectonics, which was first proposed in the early 1960s as an answer to the problems with the theory of continental drift, positing
• The case of the Missing Verb
→ Strip away the "which" clause and this sentence remains:
The theory of plate tectonics . . . positing that earth’s landmasses sit atop massive plates, which shift with the passage of time. 
→ The subject tectonics is not paired with a working verb.
Positing is a gerund (a verbING word), not a verb.
→ A common GMAT trap lurks in this sentence, although that trap is a bit more obvious because the "which" clause is set off by commas.
The trap?
GMAT writers attach a relative clause to a noun such as
theory.
Most relative clauses begin with
who, that, or
which.Relative pronouns are subjects of their own clauses and
require a verb.
GMAT writers give a verb to the relative pronoun but not to the main subject, thus producing a fragment, as is the case here.
In other words, when you see a relative pronoun, keep your wits about you and start looking for at least
two working verbs in the sentence.
At least one verb must be attached to the main subject.
Another verb must be attached to the relative pronoun.
In other words, relative pronouns "eat up" at least one working verb, so you should see at least two working verbs, because the subject of the sentence needs a verb, too.
ELIMINATE A
Quote:
B) tectonics, first proposed in the early 1960s as an answer to the problems with the theory of continental drift, and posits
• AND posits?
→ The word
and suggests that another verb precedes
posits.No such verb exists in this sentence.
ELIMINATE B
Quote:
C) tectonics was first proposed in the early 1960s as an answer to the problems with the theory of continental drift, [AND] posits
This sentence uses the verbs
was proposed and
posits in parallel structure, but we need an
and before
posits to make the use of these two verbs grammatical.
This sentence is not really a comma splice. The latter consists of two full clauses "stuck together" with nothing more than a comma. (Illegal move.)
This sentence contains a compound predicate (two verbs that share a subject) that is missing the word "and" in between the two verb phrases.
ELIMINATE C
Quote:
D) tectonics, which was first proposed in the early 1960s as an answer to the problems with the theory of continental drift, and which posits
• Another case of the Missing Verb
→ The main subject, theory, is not attached to a working verb, and thus we have a fragment.
→ As I mentioned beneath option A, the repeated relative pronoun (
which . . . and which) "eats up" the two working verbs (was proposed and posits), leaving no verb for the main subject.
You are allowed to have many relative pronouns such as
which refer back to the main subject of the sentence (and steal all the verbs from the latter in common GMAT trap questions).
ELIMINATE D
Quote:
E) tectonics, which was first proposed in the early 1960s as an answer to the problems with the theory of continental drift, posits
• I do not see any errors
• the subject
theory takes the verb
posits (again, remove the "which" clause, and you will see that in this option, the main verb for the main subject remains).
• the relative pronoun
which takes the verb
was first proposedKEEP
Option E is correctCOMMENTSAnswers in the posts are solid.
Keep up the good work.
close
06 Jul 2021, 20:56
23%
(01:30)
wrong 
