Until quite recently, American economists have assumed that

OFFICIAL EXPLANATION


THE PROMPT


THE OPTIONS
• between is used for comparison of two things whereas among is used for comparison of more than three things
-- the two things being compared do not have to be singular (both jobs and job seekers are plural -- we are comparing two groups of things)
-- being should be is
-- this sentence is contains a condition/result structure. The word IF is missing: economists have assumed that IF the unemployment rate . . .
-- if this sentence were written correctly, it would be a zero conditional. I discuss conditionals below
Eliminate A

• we need between, not among
• "there IS": okay
-- Should the unemployment rate be is grammatically identical to if the unemployment rate is.
-- correct: . . . should the unemployment rate be four percent, there is a rough balance between jobs and job seekers.
• we do not have to address the conditional issue because among is ungrammatical
Eliminate B

• we can use were in this way to mean IF it were the case that
-- there is no subject/verb problem. This were verb gets "fronted"—put before the subject.
-- in a hypothetical statement, we use simple past for the IF clause, which is also the hypothetical subjunctive
-- whether the noun is plural or singular, it takes WERE
• Correct examples
-- If I were a magician, I would poof myself to another city. (Is poof a verb? It is now.)
-- If she were less impulsive, she would not worry her family so much.
-- If poor students were given real opportunity, they would stand a fighting chance.

• A sentence that uses were in the IF/condition clause requires would in the MAIN/result clause
Corrected: . . . economists have assumed that were the unemployment rate four percent, there would be a rough balance between jobs and job seekers.
• This Type 2 conditional is not appropriate for this sentence. Economists were not hypothesizing about an unreal past.
Eliminate C

[/quote]
• this sentence is a zero conditional—in this case, a general truth [that economists assumed until recently].
• Zero conditional: IF simple present, THEN simple present
• between is correct
KEEP

E) Until quite recently, American economists have assumed that there is a rough balance among jobs and job seekers when there is an unemployment rate that is four per cent
• only one thing is wrong with this sentence: among
• in zero conditionals, we are allowed to use the word when rather than if
Eliminate E

The answer is D

• NOTES

Conditionals on the GMAT often do not contain the word IF.
Still, if a condition and result exist in the sentence (or a cause and an effect), we have a conditional.
In English, we talk about various levels of certainty with very specific verbs.

There are five types of conditional: Zero, Type 1, Type 2, Type 3, and Mixed Conditional.
You can see a general overview of all five kinds in my post, here, in the footnote

Focus on the first three.

Zero conditional: If THIS thing happens, THAT thing happens.
-- presents a general truth, scientific fact, or the like.
-- use IF simple present, THEN simple present.
-- the situation is real and possible. The statement is true now and always.

Because the statement is always true, we can use WHEN rather than IF in zero conditionals.
I explain why we can use when [without its referring to an actual time!] in this post, here (the question is good - I'd try it)

Type 1: If THIS thing happens, THAT thing WILL happen
-- mostly used for predictions, in part because the statement is made in the present about a hypothetical but real and very possible future
-- IF simple present, THEN simple future
-- condition is real, outcome ("truth") is very probable

TYPE 2 - three iterations.*
We care the most about the true hypothetical.
We use the subjunctive because we are talking about a contrary-to-fact situation.

Type 2, hypothetical: If THIS thing were to happen, then THAT thing would happen
-- If antitrust laws were enforced properly, then oligopolies would not control entire sectors of the economy.
-- these statements are about the unreal past. Neither the condition nor the result happened.
-- We use the hypothetical subjunctive (simple past WERE) to express the counterfactual nature of the situation

Without other errors, options A, B, and E would be zero conditionals, just as is option D.
If the unemployment rate IS four percent, [then] there IS a rough balance between job seekers and jobs.
We could also say, as in option E,
WHEN the unemployment rate is four percent, there IS a rough balance between job seekers and jobs.

Only Option C contains the contrary-to-fact hypothetical (the unreal past). That Type 2 conditional is the wrong construction for this kind of statement.

Many of you analyzed (C) correctly. Nicely done.

Takeaways:
• WERE is okay on its own, but only if the statement warrants a hypothetical, and this statement does not.
You may see three IF statements that use different words. All three contain "fronted" verbs.
-- WERE I you, I would call her. (If I were you, I would call her.)
-- SHOULD the current president be reelected, she will leave her country and become an expat. (If the current president IS reelected, she will become an expat.)
-- HAD I to redo that essay, I would include subject XYZ. (If I were to redo that essay, I would . . . )
• The kind of statement in this question can be a zero conditional.
-- some people mistakenly believe that zero conditionals are only hard core math or science facts.

COMMENTS

adityapanda , welcome to SC Butler. (Great username.) Nice work, by the way.

Very good to see everyone! Even though reasoning was off here and there in some posts, everyone gets kudos.



**The other Type 2s
IF simple past, then present conditional (VERY rare)
Type 2b: If THIS thing happened, then THAT thing would happen
-- If you left the house earlier, then you would be on time for the bus.
(But you did not leave the house earlier, and you were not on time.)

IF simple past, then present continuous conditional (VERY rare)
Type 2c: If THIS thing happened, then THAT thing would be happening
-- If I understood the joke, I would be laughing. (But I don't understand the joke, so I am not laughing.)