acc. to you
"adenosine binds to more and more sites on cells in certain areas of the brain" creates wakefulness

acc. to me what you got is opposite of what is stated.
if you read it you will find: As the total amount released gradually increases during wakefulness, adenosine then binds to more and more sites on cells in certain areas of the brain.

there is a cause and effect situation, but you got a reversal of it.

Thanks = KUDOS

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The question is : Which among the following strengthens the theory that adenosine, released by brain cells controls the sleepiness/ wakefulness of a person:

A) Eliminate - Since it weakens the statement by saying adenosine remains high even after long hours of sleep - meaning, the person would never wake up - thus proving the reearchers wrong.

C) Eliminate - Wedont care about the additional things it does apart from controlling sleep.

D)Eliminate - We dont care about which cells secrete adenosine and which doesnt.

E) Eliminate - Like A this also weakens researchers hypothesis as it introducing exceptions to their theory.

B) Correct - Caffeine, which is a well known component that has the effect of making people remain wakeful interferes with adenosine - meaning adenosine in the brain is used/ stimulated to induce something related to wakefulness - so adenosine is related to remaining wakeful.

I am not an expert but this was how i solved this qn.

The argument says the chemical released (Adenosine) increases gradually during wakefulness and binds itself more and more to brain cells. When asleep, the binding process slows and the number of brain cell sites where adenosine binds itself decreases.
Hypothesis- Cumulative binding to large number of sites CAUSES the onset of sleep.
In light of this understanding, go through the answer choices.
B strengthens the hypothesis by saying that a factor (Coffee) that interferes with the binding process leads to wakefulness. This means that something that does not interfere with the process of binding or when the cumulative binding process is high or normal, it leads to the onset of sleep.