Causal-Comparative or Ex Post Facto Research Is Widely Used Because

Multiple Choice

Causal-comparative or ex post facto research is widely used because

A) such studies have greater internal validity than do quasi-experimental studies.
B) the law of the single significant independent variable can be more readily applied in ex post facto research than in experimental research.
C) it is not possible to experimentally manipulate many variables of interest .
D) Campbell and Stanley are exuberant in their praise of ex post facto research.