Question

read the passage. jonas salk and polio polio is a viral disease that produces flu - like symptoms and may occasionally cause muscle weakness or paralysis. throughout the first half of the twentieth century, the disease was common, and parents feared that their children would lose the ability to move their arms or legs. in 1947, dr. jonas salk began studying polio at the university of pittsburgh in search of an answer. he discovered three basic types of polio viruses and began to develop a vaccine that would protect against all three. testing began in 1952, with vaccinations eventually given to about two million children. the vaccine was shown to be effective and was put into general use in 1955. jonas salk became a hero and received an award from president dwight d. eisenhower. what is the main, or central, idea of the passage? jonas salk developed a vaccine that provided protection against the feared disease polio. jonas salks vaccine for polio was tested in the early 1950s and put into general use in 1955. jonas salk discovered that there were three different viruses that caused the disease called polio.

Explanation:

The passage starts by introducing polio as a feared disease. Then it details Dr. Jonas Salk's work: studying polio, discovering virus types, developing a vaccine, testing it (with large - scale testing on children), showing its effectiveness, and its general use. The other two options are just parts of the whole story. The first option encompasses the entire process of Salk's contribution to combating polio, which is the main idea.

Answer:

Jonas Salk developed a vaccine that provided protection against the feared disease polio.