Keith has a 2015 tax liability of $2,250 before taking into account his American Opportunity tax credit. He paid $2,600 in qualifying expenses, was a full-time student, was not claimed as a dependent on his parents return, and his American Opportunity tax credit was not subject to phase-out. What is the amount of his American Opportunity tax credit allowed? a. $0 b. $2,150 c. $2,250 d. $2,600 e. $4,000