Which of the following is the best explanation for why income taxes are not included in the TDSR calculation?

a. Income taxes are considered to be discretionary as they vary from Province to Province and depend on a person's deductible expenses.

b. Income tax rates are set by the government and can change annually without a lending institution's ability to adjust the ratio.

c. Borrowing customers seldom know the amount of tax they are required to pay until after they file their tax return in the following year.

d. Inflation has an impact on the tax rates charged by the different governments.