The amounts of mood-elevating chemicals in the brain are a. lower in sedentary people than in those who are physically active. b. the same in sedentary people and in those who are physically active. c. higher in sedentary people than in those who are physically active. d. present in sedentary people but nonexistent in those who are physically active.

The answer would be: A. lower in sedentary people than in those who are physically active

Physical exercise is known to boost the mood and improve many aspects of health. The substance that improves mood probably is serotonin. Serotonin is the neurotransmitter that will make you feel have much energy and happy. Serotonin production will be increased by physical exercise. Sedentary is a term that used to describe a person that mostly sitting and little physical exercise. 

The answer is A: lower in sedentary people than in those who are physically active.