Cyclic GMP, or cGMP, acts as a signaling molecule whose effects include relaxation of smooth muscle cells in artery walls. In the penis, this signaling pathway and the resulting dilation of blood vessels leads to an erection. Select the correct statement about the effect of Viagra on this signaling pathway.
A. Viagra increases the rate of hydrolysis of cGMP to GMP.
B. Viagra inhibits the hydrolysis of GMP to GMP.
C. Viagra prevents the formation of cGMP.
Answer: B