Jessie, an unmarried taxpayer using the single filing status, received $16,000 of Social Security retirement benefits in 2019. Jessie also received $5,000 of interest income and $75,000 of income from her retirement plan during the year. How much of Jessies Social Security benefits must be included in her gross income? 1. $0. 2. $13,600. 3. $16,000. 4. $8,000.