Prep SC. Several educational research groups are

[MARSHALLM603]

Dear Instructors:

Sorry to open a new thread about an existing question, since the old topic has been locked, and no post is allowed in that thread.

The topic is: https://www.manhattanprep.com/gmat/foru ... ups#p83385

Several educational research groups are denouncing the mayor's proposal of a system by which individual teachers would be given raises or bonuses should it be that test scores show their students' mastery of reading skills having improved over a nine-month period.

(A) should it be that test scores show their students' mastery of reading skills having
(B) should it be that test scores show their students' mastery of reading skills have
(C) should test scores showing their students' mastery of reading skills has
(D) if test scores showing their students' mastery of reading skills having
(E) if test scores show that their students' mastery of reading skills has

The correct answer is OE.

I have a question regarding to the OA, option E:

I know that the subject is mastery, and thus "has" is used as a singular form here, however, isn't the complete subject "their students' mastery"? I mean student's mastery is singular, but students' mastery means mastery of "more than one student", isn't it plural?

Could anyone pls help, thanks!

[RonPurewal]

per the forum rules, please post the entire problem exactly as originally provided, with all answer choices (and with the correct answer indicated).
thank you.

[MARSHALLM603]

per the forum rules, please post the entire problem exactly as originally provided, with all answer choices (and with the correct answer indicated).
thank you.

Sorry Ron. Question modified.

[RonPurewal]

"mastery" is still singular. it makes no difference what descriptors are attached.

i mean, i'm 100.00000% sure that you already know this.
e.g.,
His house is big.
Their house is big.

i'm assuming it's perfectly clear that you wouldn't write "Their house are big".
that's clear, right?