A New Vasopressor in Development, Drug X, Is a Partial

A new vasopressor in development, Drug X, is a partial agonist at a1- adrenergic receptors. Epinephrine is a full agonist at these same receptors. Which of the following statements is true regarding the potency of Drug X compared to epinephrine?

A) Drug X and epinephrine are equally potent because they act on the same receptors
B) Drug X is more potent because it is a partial agonist
C) Epinephrine is more potent because it is a full agonist
D) Epinephrine is more potent because it is an endogenous neurotransmitter
E) Relative potency cannot be determined from the information given