Which of the following statements suggests that property taxes might be progressive?

a. The proportion of income spent on housing tends to decline as income rises.

b. Higher-income people live in more expensive houses than do low-income people.

c. A large part of the property tax is shifted to renters, who typically have lower incomes than owners.

d. Inner city neighbourhoods often have higher property taxes than do the more affluent suburbs.

e. Elderly pensioners often live in their family homes after children have left.