Final answer:
The shorter DR (dose-response) curve on the Y-axis indicates a more potent and efficient drug, which is an agonist. Option c
Step-by-step explanation:
The DR (dose-response) curve represents the relationship between the dose of a drug and its effect. A shorter DR curve on the Y-axis implies that a lower dose of the drug is required to produce a maximal effect. In this case, the correct answer is c.
Agonist because an agonist is a drug that binds to and activates a receptor, resulting in a biological response. The lower dose requirement of an agonist compared to other options on the list indicates a more potent and efficient drug. Option c