11. Nancy and Nathan are married and file a joint return for 2020. Nancy is 60 years old and Nathan is 67 years old, both have good vision. They receive total Social Security benefits of $10,000 per year. They have total pension income of $18,000 from a corporate retirement plan. How much of the Social Security benefits should be included in income on their tax return? O $0 O $12,800 O $10,000 O $8,500