As Possible Vasoconstrictors, Three Alpha-Agonist Medications Are Investigated

As possible vasoconstrictors, three alpha-agonist medications are investigated. By measuring the cross-sectional area of a single, isolated vessel following medication administration, the degree of vasoconstriction may be ascertained. The obtained curves are as follows: Which of the following is the best statement concerning the effects of these drugs?

A) Drug 1 has lower potency than Drug 2
B) Drug 2 has higher affinity for alpha-receptors than Drug 3
C) Drug 1 demonstrates the highest efficacy
D) Drug 2 and Drug 3 bind to different loci of alpha-receptors
E) Drug 2 and Drug 3 demonstrate a similar potency