Virginia is a cash-basis, calendar-year taxpayer. Her salary is $90,000, and she is single. She plans to purchase a residence in 2020. She anticipates her property taxes and interest will total $8,100. Each year, Virginia contributes approximately $4,000 to charity. Her other itemized deductions total approximately $3,700. For purposes of this problem, assume that 2020 tax rates and standard deductions are the same as for 2019.

a. What will her gross tax be in 2019 and 2020 if she contributes $4,000 to charity in each year?

b. What will her gross tax be in 2019 and 2020 if she contributes $8,000 to charity in 2019 but makes no contribution in 2020?

c. What will her gross tax be in 2019 and 2020 if she makes no contribution in 2019 but contributes $8,000 in 2020?

d. Alternative c results in a lower tax than either a or b. Why?