What was one of the challenges dr. salk faced in his attempt to create a polio vaccine?

“Polio was never the raging epidemic portrayed in the media, not even at its height in the 1940s and 1950s,” writes David M. Oshinsky in his Pulitzer Prize winning book “Polio: An American Story.” During those decades, 10 times as many children died in accidents and three times as many succumbed to cancer. Oshinsky notes that polio inspired such fear because it struck without warning and researchers were unsure of how it spread from person to person. In the years following World War II, polls found the only thing Americans feared more than polio was nuclear war.

A year after his nomination as a Democratic vice presidential candidate, rising political star Franklin D. Roosevelt contracted polio while vacationing at his summer home on Campobello Island in 1921. The disease left the legs of the 39-year-old future president permanently paralyzed. In 1938, five years after entering the White House, Roosevelt helped to create the National Foundation for Infantile Paralysis, later renamed the March of Dimes Foundation, which became the primary funding source for Salk’s vaccine trials. Employing “poster children” and enlisting the star power of celebrities from Mickey Rooney to Mickey Mouse, the grassroots organization run by Roosevelt’s former Wall Street law partner Basil O’Connor was raising more than $20 million per year by the late 1940s.

the answer is c or the third one.

are you asking true or false