Which of the following statements is incorrect regarding the exclusion for Series EE bond interest?

a. To be eligible for the exclusion, married couples must file a joint tax return.

b. The exclusion is not available if when the bonds were acquired, the person who bought the bonds was under the age of 24.

c. Qualified expenses include tuition and fees, but not room and board.

d. A reduction in the initial amount of the exclusion applies to single taxpayers starting once their modified AGI exceeds $113,950.