The social security administration faces new challenges in the twenty-first century because

a. there are more workers paying into the system.
b. its services are no longer needed by american workers.
c. there are a greater number of retirees in the system.
d. its revenues are needed in other government programs.

C.there are a greater number of retirees in the system.

Although the United States has not yet faced the challenges of an aging population in the way that countries such as Japan have, the population of the country is aging, and this will be a significant challenge to the Social Security Administration in the coming years. The number of Americans over the age of 65 is projected to double, from 46 million in 2016 to over 98 million by 2060. Moreover, their share of total population will rise to nearly 24% (from 15% in 2016).