A researcher investgating depression devises a study that contains the independent variable "Treatment," manipulated between-participants. Participants may experience "psychodynamic therapy," "cognitive behavioral therapy," "medication," or "waiting list placement." How many levels does the variable contain?

a) There are four levels to the variable.

b) There are three levels and a control condition.

c) There are four levels and "Treatment," making five.

The number of levels in a variable refers to the number of distinct conditions or categories within that variable. In this case, the independent variable "Treatment" has four levels: "psychodynamic therapy," "cognitive-behavioral therapy," "medication," and "waiting list placement." Therefore, the correct answer is a) There are four levels to the variable.