Definition: In this task, you're given a question, along with a context passage. The passage will not have a direct answer to the question, but can include some information and a clue for the answer. Assuming you can only obtain information about one entity in the passage, your job is to determine whether information from the passage can be used to answer the question. Indicate your choice as `a` for Yes or `b` for No.
Input: Question: Where was McMahon's post-doctoral mentor from? Passage:McMahon contributed to the understanding of retinal neurophysiology alongside his post-doctoral mentor, John E. Dowling. His early research focused on ion channels that mediate transmission at electrical and glutamatergic synapses and the modulatory effects of dopamine and nitric oxide on retinal synapse networks. Through studies with zebrafish he discovered that the neurotransmitter dopamine decreases the electrical coupling within horizontal cells. Further research showed that it was the increase of cAMP within the cell resulting from dopamine binding to AMPA receptor that led to this decrease in coupling. McMahon and his colleagues also demonstrated that exogenous nitric oxide and zinc can modulate AMPA receptor mediated synaptic transmission at gap junctions in hybrid bass retinal neurons.


a