When thinking about GREs, applying to graduate school, and studying for mid-terms, Nichole starts to have sweaty palms and a racing heart. It is MOST probable that Nichole is responding to T cells:. 1. the pressure. 2. stressors. 3. lymphocytes. 4. cytokines.

stressors

Explanation:

In this Nichole responding to stressors, as stressor is any event or external environment stimulus which make people challenging and threatening, than stress hormones activate.  So in this situation as stress hormones activate, his body respond like  sweaty palms and a racing heart.  In simple when person unable to cope or handle the situation and feel demanding stress hormones release and human body respond according to that.