Final answer:
Mark's BMR will increase due to his fever. Therefore, the correct answer is A. BMR will increase.
Step-by-step explanation:
Mark's BMR would be affected by his fever.
A fever is an increase in body temperature. According to the information provided, for every increase of 0.5°C in internal temperature, the BMR increases by about 7%. So, with a fever of 99.6°F, Mark's BMR would increase.
Therefore, the correct answer is A. BMR will increase.