In December 2015, Gary, a cash basis taxpayer, paid $1,200 fire insurance for the calendar year 2016 on a building he held for rental income. He deducted the $1,200 insurance premiums on his 2015 tax return. He had $150,000 of taxable income that year. On June 30, 2016, he sold the building and, as a result, received a $500 refund on his fire insurance premiums. As a result of the above:

A. He should include the $500 in 2016 gross income in accordance with the claim of right doctrine.

B. He should add the $500 to his sales proceeds from building.

C. He should include the $500 in 2016 gross income in accordance with the tax benefit rule.

D. He should amend his 2015 return and claim $500 less insurance expense.

E. None of these choices are correct.

Please explain why is that your answer. Please make it understandable.