The available blood supply is just one pint each of A+, AB-, B-, and O+. Which pint must each of
the four patients receive?

Patient 1: B- (Answered)
Patient 2: AB- (Answered)
Patient 3. A+ (Answered)
Patient 4. O+ (Answered)

(Help) Explain your reasoning for distributing the pints of
blood the way that you did.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.  

i'm thinking 600 feet deep in one of the finger lakes.