25. In 2018, Jake and Mary Jacobs, a married couple, have specially modified adjusted gross income of $25,000 and $10,000 in social security benefits. If the Jacobs file a joint return, what portion of their social security benefits are included in income for federal income tax purposes?

a. $10,000

b. $5,000

c. $2,500

d. $1,000

e. $0