When a group of people must decide whether to buy a shared public good or service, the free-rider problem frequently occurs because:
a. People have an incentive to understate how much the facility is really worth to them if they have to pay taxes to finance it.
b. Each individual's needed contribution is an insignificant amount of the total required.
c. People have an incentive to overstate how much the facility is worth to them if they don't have to pay taxes to finance it.
d. People hope that others will value the facility enough to pay for it entirely.
e. Only one of the above statements is not a reason for the existence of the free-ride problem.