Why do males tend to have better cardiorespiratory fitness than females?

a. males tend to have higher levels of hemoglobin in their blood.

b. females tend to have higher levels of hemoglobin in their blood.

c. males tend to have higher levels of body fat than females.

d. females tend to have more lean muscle mass than males.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands