Jody, an unmarried taxpayer using the single filing status, received $17,000 of Social Security retirement benefits this year. He also received $5,000 of interest income and $50,000 of income from his retirement plan during the year. How much of Jody's Social Security benefits must be included in his gross income this year?

A)$0

B)$8,500

C)$14,450 (Please provide a detail explanation if the answer is or isn't C. Thanks.

D)$17,000