There are two kinds of substances that occupy a neural receptor. Which kind of substance blocks normal synaptic transmission? A) agonist
B) interior colliculus
C) antagonist
D) superior colliculus

again, you should probably take him to the vet. goodluck

what are the choices?

during longer space exploration trips, crewmembers may develop vision impairment risks and short-term cardiac atrophy or a decrease in the size, strength, weight, and activity of the heart during space flight because they can experience microgravity. in addition, the long-term medical condition is loss of bone mineral density and radiation exposure.