Forty multiple choice exercises$/$problems appear below. You must answer all of them. For each problem you answer, insert the letter which indicates the correct answer in the appropriate space on the separate answer sheet. All final answers have been rounded to the nearest $$10.$

$1.$ Spouses Bill and Betty Baker, ages $78$ and $69,$ maintain and reside in a home in which Betty's mother, Bertha, also lives. Bertha is age $92$ and blind with zero gross income. Bill and Betty provide $100\%$ of Bertha's support. What standard deduction will Bill and Betty claim on their joint federal income tax return for the year?

$$ A$$ $$30,700$

$27,700$ c $28,700$ D $29,200$

$$ None of the above