Which of the following statements concerning Dipyridamole is true?

a) Dipyridamole is an agent that blocks the reabsorption and breakdown of adenosine that results in an increase of endogenous adenosine and vasodilatation

b) The drug causes relative hypoperfusion of myocardial regions served by coronary arteries with haemodynamically significant stenoses

c) Dipyridamole is a platelet aggregation inhibitor

d) All of the above