Which of the Following Statements About the Response of Arteriolar

Which of the following statements about the response of arteriolar smooth muscle to changing oxygen partial pressures is TRUE?

A) Both systemic and pulmonary arterioles respond to a decrease in P_O2 by constricting.
B) Both systemic and pulmonary arterioles respond to a decrease in P_O2 by dilating.
C) Systemic arterioles respond to a decrease in P_O2 by dilating, but pulmonary arterioles constrict in response to decreased P_O2.
D) Systemic arterioles respond to a decrease in P_O2 by constricting, but pulmonary arterioles dilate in response to decreased P_O2.
E) Changes in P_O2 do not affect arteriolar smooth muscle in the pulmonary system.