An Advantage of Matching Over Holding a Variable Constant Is

Multiple Choice

An advantage of matching over holding a variable constant is that

A) it may restrict the generalizability of the results.
B) within a group the confounding variable does not vary.
C) for each individual in one group there is a comparable individual in each of the other groups who has the same value on the confounding variable.
D) all individuals within a group have the same value on the confounding variable.