Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: Figure 36.20 When light strikes rhodopsin, the G-protein transducin is activated, which in turn activates phosphodiesterase. Phosphodiesterase converts cGMP to GMP, thereby closing sodium channels. As a result, the membrane becomes hyperpolarized. The hyperpolarized membrane does not release glutamate to the bipolar cell. Answer: phosphodiesterase
When light strikes rhodopsin, the g-protein transducin is activated, which in turn activates what?