any verbal expert please explain why we rejected c.

daagh A is clearly the answer here, but could you help with what's wrong with D?

Am really confused now.
As per discussion on https://gmatclub.com/forum/canadian-sci ... 01939.html, it is said Should is reserved for recommendations and should not be used to express probability.
how can the OA be A then?

daagh Sir,

In option A how the use of "should" is justified?
Because of "should" I went with Option D which is grammatically correct but not maintaining exact meaning.

Please explain.

Thanks in advance
Rishit

daagh: I agree thats correct. But can you comment on the validity of the link i posted above? It explicitly states should is to be used for recommendations/obligations.. and not to denote possibility

[quote="ajh258"]If this is how GMAT works, this is how it works. However, from a native speaking and meaning perspective, there's clearly a big flaw in the official correct choice.

Thanks ajh258 for stating this as per a native's perspective, coz i thought on similar lines and marked 'C' option only to find it was wrong option. Also, I couldn't and still not able to comprehend the solution given in the OA!!

OFFICIAL EXPLANATION:


Rhetorical Construction; Diction

The sentence considers some possible mechanisms by which cheddar cheese might inhibit tooth decay. The underlined portion of the given sentence may express a certain skepticism, signaled by the use of why … should, as to whether cheddar cheese does, in fact, inhibit tooth decay, and the rest of the sentence attributes to Dr. Bowen a speculation as to how this might occur. The expression why … decay is a noun clause and the subject of the verb is.

A Correct. As explained above, this version of the sentence is clear and grammatically in order.
B This answer choice is incoherent. Because it is nonsensical to say that cheddar cheese is not clear, cheddar cheese cannot be taken as the subject of the verb is; the phrase cheddar cheese and is therefore best viewed as a fragment that does not fit grammatically in the context.
C This version appears intended to indicate that no clear mechanism by which cheddar cheese inhibits, or could inhibit, tooth decay has been described. Because the concern about a mechanism would presuppose that cheddar cheese does, or could, inhibit tooth decay, the use of should to indicate doubt as to whether this is so does not fit well in context.
D The intended thought in this answer choice may be something like the following: it is unclear that cheddar cheese inhibits tooth decay, and how [it would do so]. But this is not correctly expressed. The verb is seems to have two subjects, the that-clause and the implicit how-clause, so the verb form should be the plural are.
E This answer choice is unnecessarily awkward and wordy, with the use of there is and the unnecessary use of the noun inhibition instead of a form of the verb inhibit.

The correct answer is A.

After take a look among the answer choices, I hope everybody get the final decision betwen A and C.

Why A and not C?

C) How cheddar cheese should inhibit tooth decay is not clear -> "HOW" tell us that we are 100% sure that cheese cheedar does inhibit tooth decay (we just want to know how is the process), but if we add the word "should", we are giving a space to doubt about the capacity of cheedar cheese to inhibit tooth decay, so use "How" and "Should" in the same clause is a contradiction. This contradiction doesn't occur in answer choice A.