Question: In the process of phototransduction in the retina, what critical role does guanylyl cyclase play? A) Guanylyl cyclase activates rhodopsin, initiating the phototransduction cascade B) Guanylyl cyclase catalyzes the conversion of cGMP to GMP, leading to hyperpolarization of photoreceptor cells C) Guanylyl cyclase deactivates phosphodiesterase, preventing the breakdown of cGMP and maintaining photoreceptor cell sensitivity in darkness D) Guanylyl cyclase synthesizes cGMP in response to light, maintaining photoreceptor cell depolarization