The following information applies to the questions displayed below.] In 2021, Elaine paid $2,800 of tuition and $600 for books for her dependent son to attend State University this past fall as a freshman. Elaine files a joint return with her husband. What is the maximum American opportunity tax credit that Elaine can claim for the tuition payment and books in each of the following alternative situations? (Leave no answer blank. Enter zero if applicable.)

a. Elaine's AGI is $80,000

b. Elaine's AGI is $168,000.

c. Elaine's AGI is $184,000.