Which of the following statements is true?
a. arteries carry only oxygenated blood.
b. the systemic circuit leaves the heart from the left ventricle.
c. blood never passes through more than one capillary bed on its trip through the systemic circuit.
d. platelets survive a longer time than erythrocytes.
e. blood from the pulmonary system returns to the heart at the right atrium.

The true statement is option B.

Explanation:

The systemic circuit is the component of the circulatory system, which carries the blood from the heart, and supply it to the majority of the organs and tissues, and returns it back to the heart. The oxygenated blood from the lungs goes into the left atrium and is mediated towards the left ventricle in order to supply the blood to the organs of the body.  

The systemic circuit is different from the pulmonary circuit that only mediates blood between the heart and lungs.  

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