if someone could help with this would it be c
Yeah, that's correct!
a is wrong because it says atropine and acetylcholine are similar shaped (not complementary), so they wouldn't bind together.
b would be wrong because it couldn't hyperpolarise the cell by binding to the receptor on channels, something binding would either do nothing (channels remain closed) or cause the channel to open and let in positive ions to depolarise the neuron and bring about an AP.
pls correct me if i've explained this wrongc yeah they are similar shaped so would be competing for the binding spot as they can both fit
d atropine would be an antagonist (not agonist) as it wouldn't produce APs as it says in the stem.