Olympic athletes have lower resting heart rates
a. their lungs tend to be naturally larger.
b. they exercise regularly, which improves the efficiency of their heart.
c. they tend to eat low-fat diets.
d. they have a lot of muscle mass due to weightlifting.

true

explanation:

a genogram (also known as a mcgoldrick-gerson study, a lapidus schematic or a family diagram) is a pictorial display of a person's family relationships and medical history. it goes beyond a traditional family tree by allowing the user to visualize hereditary patterns and psychological factors that punctuate relationships.