Video Explanation

Text Explanation

Split 1: pronoun agreement

The subject of the VP’s statement is the “proposed alloy”—the VP’s statement is about the advantages of this alloy.  Since “alloy” is singular, we need the singular pronoun “it.” Choices (C) & (D) use “their” and are incorrect.

Split #2: the Inside/Outside rule

One important rule about parallelism is the Once Outside, Twice Inside rule.  This rule comes into effect when we have correlative conjunctions—that is, a coupled pair of conjunctions marking the two halves of the parallelism: examples include “both X and Y,” “neither X nor Y,” “not X but Y,” and “not only X but also Y.”  When any of these are used, the parallelism has a clear start at the beginning of the first word. Anything that is within the “both X and Y” structure is “inside,” and anything that comes before or after it is “outside.” Now, suppose a preposition applies to words in both branches of the parallelism.   We have two options:

Once Outside: to both X and Y

Twice Inside: both to X and to Y

The mistake patterns:

One inside: both to X and Y

Once outside, once inside: to both X and to Y

In this question, the correlative conjunction we use is “not … but.”  When we look at the second half, we see “but in”—in other words, the word “in” appears, but the word “lie” does not appear.   Thus, the word “lie” must appear once outside, and the word “in” must appear twice inside. The structure we need at the beginning is “lie not in.”  Only choice (B) gets this correct.

Choice (A) & (D) but the verb “lie” after the word “not,” so that it appears once inside, one of the mistake patterns.   

Choice (C) & (E) have the proposition “in” appears before the word “not,” so that is appears once outside, once inside—the other mistake pattern.   

The only possible choice is (B).