If research clearly established that "study time determines the grades that a student earns," grades are the _____ variable.

A) dependent
B) independent
C) control
D) intervening

In this scenario, the grades earned by the student are the output or the dependent variable, as they depend on the amount of time the student spends studying, which is the input or the independent variable. Control variables are other factors that might impact the student's grades but are held constant or controlled for in the study (such as intelligence, motivation, or teacher quality). Finally, intervening variables are those that might mediate or explain the relationship between time spent studying and grades earned (such as interest in the subject, quality of study materials, or stress levels).