Amedical student is studying how the volume of blood in the circulatory system affects blood pressure. he measures the blood volume and pressure of two classmates, a man and a woman. he finds that the man has a higher blood volume but a lower blood pressure than the woman. he concludes that a person with low blood volume would tend to have high blood pressure. what additional factors should the student consider that would most likely affect blood pressure?

a. differences in overall outlook on life
b. differences in size and gender
c. differences in the day's food intake
d. differences in the amount of recent exercise