Nicotinic Receptors Are ___ and Are Found ___;Muscarinic Receptors Are

Nicotinic receptors are ___ and are found ___;muscarinic receptors are ___ and are found ___.

A) excitatory,in muscles and the brain,excitatory or inhibitory,more frequently in the digestive system
B) excitatory,in muscles and the brain,excitatory or inhibitory,more frequently in the brain
C) inhibitory,in muscles and the brain,excitatory or inhibitory,more frequently in the muscles
D) excitatory or inhibitory,in muscles and the brain,excitatory,more frequently in the digestive system