If R is not reduced, which one of the following must be true?

Lizzie-Annerino on July 31, 2019

Why not B?

Why is the correct answer not B?

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Ravi on August 1, 2019


Let's take a look at (B) and (A).

If R is not reduced, then we know that L and M must both be reduced.

If L is reduced, then we know that P is not reduced. This means that P
and R occupy 2 of the 3 "not reduced" slots.

Recall the rule that states if N is reduced, neither R nor S is
reduced. We know that R isn't reduced, so the necessary condition for
that part of the rule is satisfied. However, look at the rest of the
rule. If N is reduced, then S can't be reduced. Conversely, if S is
reduced, then N can't be reduced. This means that either N or S can't
be reduced.

From this, we know that both W and G must be reduced.

(A) says G is reduced, and we know that must be true, so it's the
correct answer choice.

(B) says that N is not reduced. It's possible that N is reduced,
however. We just know that either N or S is not reduced, but it's
possible that N is the one that's reduced and S isn't reduced, so we
can get rid of (B).

Does this make sense? Let us know if you have any other questions!