At birth, which statement is true? a. Systemic resistance and pulmonary resistance fall. b. Gas exchange shifts from the placenta to the lung. c. Systemic resistance falls and pulmonary resistance rises. d. Systemic resistance and pulmonary resistance rise.

B

Explanation:

At birth, system resistance increase while pulmonary resistance decrease

b

Explanation:

Before birth, oxygenated blood comes from Placenta and goes to fetus heart through "ductus venosus" by bypasses liver. At birth, blood circulation change due to pulmonary and systemic vasuclar resistance when placenta is disconnected. Systemic resistance rises when blood flow loss through placenta. As systemic resistance rises, aortic pressure increases and in this case lungs are also expand. As lungs expand, the pulmonary vascular resistance greatly falls.