Answer:
Explanation:
1) Excitation brings about contraction.
2) Contraction leads to an increase in blood pressure.
3) Changes in blood pressure results in the opening and closing of the heart valves.
4) The opening and closing of heart valves then regulates the flow of blood and it's volume.
I think it’s C because if you’re allergic to one cillian than you’re allergic to all of them
Sorry if this is wrong