For the system to function properly, there must be enough workers paying in to support all the retired workers receiving benefits. Although the
system has worked well, changes in the U.S. population threaten to undermine it.
Which "change in the U.S. population" is this passage referring to?
O a sharp increase in the Hispanic American population
eroding popular support for entitlement programs
the growing share of the population made up of retirees
the growing number of workers who do not have taxes withheld from their paychecks