Figure 16-20 shows the pathway through which nitric oxide (NO) triggers smooth muscle relaxation in a blood vessel wall.Which of the following situations would lead to relaxation of the smooth muscle cells in the absence of acetylcholine? Figure 16-20

A)a smooth muscle cell that has a defect in guanylyl cyclase such that it cannot bind NO
B)a muscle cell that has a defect in guanylyl cyclase such that it constitutively converts GTP to cyclic GMP
C)a muscle cell that has cyclic GMP phosphodiesterase constitutively active
D)a drug that blocks an enzyme involved in the metabolic pathway from arginine to NO