No one knows what purposes, if any, dreams serve, although there are a number of hypotheses. According to one hypothesis, dreams are produced when the brain is erasing “parasitic connections” (meaningless, accidental associations between ideas), which accumulate during the day and which would otherwise clog up our memories. Interestingly, the only mammal that does not have rapid eye movement sleep, in which we humans typically have our most vivid dreams, is the spiny anteater, which has been seen as anomalous in that it has a very large brain relative to the animal’s size. This fact provides some confirmation for the parasitic-connection hypothesis, since the hypothesis predicts that for an animal that did not dream to have an effective memory that animal would need extra memory space for the parasitic connections.

The parasitic-connection hypothesis, if true, most strongly supports which one of the following?
(A) The animals with the smallest brains spend the most time sleeping.
(B) Immediately after a person awakens from normal sleep, her or his memory contains virtually no accidental associations between ideas.
(C) When a mammal that would normally dream is prevented from dreaming, the functioning of its memory will be impaired.
(D) Insofar as a person’s description of a dream involves meaningful associations between ideas, it is an inaccurate description.
(E) All animals other than the spiny anteater dream.

Explanations surely help

This is a very extreme answer the word "NO" in the above it says its erasing parasitic connections but doesnt say 100% and we cannot assume it. I would go with A.

One with Small brain needs to sleep a lot - else memory will clog up..is consistent.

C for me.

C) Because the passage states, " since the hypothesis predicts that for an animal that did not dream to have an effective memory that animal....."

So it clearly implies that if a person who would normally dream is prevented from it might not have effective memory or in other words functioning of its memory will be impaired.

(A) The animals with the smallest brains spend the most time sleeping. [This is close – but it has no connection to the extra memory space – Eliminate it]

(B) Immediately after a person awakens from normal sleep, her or his memory contains virtually no accidental associations between ideas. [Fine, but does not establishes any connection to the extra memory space - – Eliminate it]

(C) When a mammal that would normally dream is prevented from dreaming, the functioning of its memory will be impaired. [Hold it]

(D) Insofar as a person’s description of a dream involves meaningful associations between ideas, it is an inaccurate description. [Why to bother for the definition of dream - Eliminate it]

(E) All animals other than the spiny anteater dream. [All animals dream is fine, but does not establishes connection to memory space – Eliminate it]

Answer: C