You only sent a graph, you need to include the question for us in order to answer.
Caffeine works as an adenosine receptor antagonists, this essentially means that it works in the opposite manner or works against the receptor. Think of antagonist in the term of literature it goes against the agonist. Adenosine when bond to the receptor causes tiredness, this is the reason why people drink caffeine to stay wake and to prevent cognitive decline from exhaustion. So caffeine doesn’t really effect learning or memory to a large extent like other stimulants do. So basically caffeine increases wakefulness which in turn allows a person to focus longer, slight increase in memory, and more of a sorted out thought process.
Genetic drift I believe because it means <span>variation in the relative frequency of different genotypes in a
small population, owing to the chance disappearance of particular genes
as individuals die or do not reproduce.</span>
