The term duration refers to
a. how strenuous a workout is.
b. how much sweat is lost during a workout.
c. how many times per week a person exercises.
d. how long a workout or exercise lasts.

The question is asking us to define the term "duration" when used for exercise - and in fact it is d. how long a work out or exercise lasts. For exmple, a duration of an exercise could be 90 minutes and the fruquency, that is how often you exercise, could be twice a week (this would be c, so if the question was asking for frequency, we would answer C)

Hiv can be transmitted through oral sex. you can get hiv through vaginal fluid and semen. if you have an open sore or cut in or near your mouth and an you get the semen or vaginal fluid of an infected person in those cuts or sores, you can get hiv

Answer charlie should immediately start an exercise and diet program because all his test indicate that he is extremely obese;