Efficiency and redundancy are contradictory characteristics of linguistic systems; however, they can be used together...

Ravi August 13, 2019

@Meredith,

Great question. The first sentence provides us with context/background
information. It's not a conclusion because it's not supported by the
rest of the stimulus. While "however" often introduces conclusions, it
doesn't always introduce them, and this question is an example where
"however" doesn't introduce a conclusion.

The question is asking us about what must be true based on what's in
the stimulus.

We have two conditional statements in the stimulus:

Completely efficient - >everything understandable
imperfect receptor - >not everything understandable

We can take the contrapositive of the second statement to form a big chain:

Completely efficient - >everything understandable - >perfect receptor

This tells us that if a spoken language is completely efficient, then
it would have to be completely understandable, which means that the
human auditory system would have to be a perfect receptor of sounds

(E) says, "If the human auditory system is an imperfect receptor of
sounds, then a spoken language cannot be completely efficient."

(E) is the contrapositive of the big chain we made, so we know that it
must be true. Thus, (E) is the correct answer choice.

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