Carrie Was Getting Less Sleep During Midterms, So She Began

Multiple Choice

Carrie was getting less sleep during midterms, so she began drinking one cup of coffee in the morning to feel more alert. By the end of the semester, Carrie was drinking three cups of coffee each morning to get the same sense of alertness. What has happened to Carrie?

A) Her nervous system has likely compensated to her prior coffee consumption by reducing sensitivity of receptors for caffeine.
B) She is experiencing withdrawal when she drinks coffee.
C) Coffee is no longer an agonist for her.
D) Coffee is no longer an antagonist for her.