Nadine Is Considering the "Dress Well,test Well" Theory,which Argues That

Multiple Choice

Nadine is considering the "dress well,test well" theory,which argues that one performs better on exams when one dresses nicer than one does when wearing sweatpants.If Nadine wants to test this theory over the course of the semester,which of the following would be an endogenous factor in her experiment?

A) her innate ability in the subject
B) the difficulty of the exam
C) the relative mix of multiple-choice and short-answer questions
D) her clothing choice for the exam
E) the amount of time Nadine spends studying for the exam