Successful Drugs Have Been Discovered by Which of the Following

Multiple Choice

Successful drugs have been discovered by which of the following methods?

A) chance observation of a beneficial, though unplanned, physiological effect
B) screening natural products with interesting activities
C) combinatorial chemical synthesis of large collections of chemically related compounds for screening
D) if the structure of the target is known, computer-aided design of compounds that might bind to the target
E) All of the answers are correct.