Aresearcher has designed a study to test the effects of different types of individual psychotherapy on people's levels of depression. she has randomly assigned people to one of three groups: a cognitive-behavioral treatment group, a psychodynamic treatment group, or a no-treatment control group. she then measures people's level of depression after the treatment. which of the following statements is true?
a) the treatment group is the dependent variable; depression is the independent variable.
b) depression is the dependent variable; the treatment group is the independent variable.
c) depression is the dependent variable; cognitive-behavioral treatment is the independent variable.
d) cognitive-behavioral treatment is the dependent variable; depression is the independent variable.