Because people enjoy the benefits of public goods whether they pay for them or not, people are usually ________ to pay for them. This is known as the free-rider problem, and is intrinsic to ________ goods.

A) willing; private
B) willing; public
C) unwilling; private
D) unwilling; public

Public goods are non-excludable and non-rivalrous, meaning people cannot be easily excluded from using them and one person's use does not reduce availability for others. This leads to the free-rider problem, where individuals may benefit from goods without contributing to their cost, making people generally unwilling to pay for them voluntarily.