An educator evaluates the effects of small, medium, and large class sizes on academic performance among male and female students. identify each factor and the levels of each factor in this example. (select all that apply.)

a. gender (two levels: male, female)
b. academic performance (three levels: above average, average, below average) class size (two levels: small, large)
c. academic performance (two levels: passing, failing)
d. class size (three levels: small, medium, large)
e. gender (three levels: male, female, trans)