Question 54 of 75. Richard (69) and Karen (73) are married, live together, and file a joint return. Their gross income for the tax year was $32,000 which does not include Karen's social security benefits of $15,600. Richard has not started collecting social security benefits yet. Choose the response that best completes this sentence: Up to of Karen's social security benefits may be taxable. 0% 50% 85% 100% Mark for follow up action 55 75