Question

precapillary sphinctors control the opening and closing of capillary beds.
a true
b false

Explanation:

Precapillary sphincters are smooth muscle cells located at the entrance of capillary beds. They can contract or relax to regulate blood flow into the capillary beds. When they contract, blood flow into the capillary bed is restricted (closing), and when they relax, blood can flow into the capillary bed (opening).

Answer:

A. True