A single retired taxpayer has Social Security income of $8,500 and some small self-employment income of $350. Are they required to file a return, and if so, what is their gross income? Select one: a. Yes; Their gross income is $8,500, but the self-employment income is below the treshold and is not needed on the return. b. Yes; Their gross income is $8,850 since both forms of income are taxable. c. No; The self-employment income is not over the reporting threshold and the Social Security income is not taxable. No return is necessary to be filed because they are below the filing requirement limit. d. Yes; Their gross income is $350 from the self-employment but the Social Security is not taxable