Final answer:
The sympathetic nervous system controls the body's response to stress and its functions include increased heart rate, pupil dilation, vasoconstriction, and inhibition of digestion.
Step-by-step explanation:
The sympathetic nervous system controls the body's response to stress and is responsible for the fight-or-flight response. Its main functions include increased heart rate, pupil dilation, vasoconstriction, and inhibition of digestion. Therefore, the correct answer is B. Pupillary constriction, as dilation is the function of the sympathetic nervous system.