Some students work hard in school in order to get high grades. based on this information, these students are motivated by
a. homeostasis
b. drives
c. incentives
d. instincts

One way to describe this situation is that the grades are a reward for those students. Another way to say is is that the students were working towards their incentives - the answer is c).

Drives and instincts are more driven by the current situation  rather than the future goals and incentive is more about the future goal and benefit of the work rather than the current need.

The adams apple, or laryngeal prominence. is a feature of the human neck, and is the lump or protrusion that is formed by the angle of the thyroid cartilage surrounding the larynx seen especially in males.