Two Matched Groups Critics Have Challenged the Internal Validity of Brady's

Multiple Choice

Two Matched Groups Critics have challenged the internal validity of Brady's (1958) study of ulcers in monkeys.Select the design that allows us to compare "executive" and "nonexecutive" monkeys and prevents selection threat.

A) experimental group-control group design
B) multiple groups design
C) two experimental groups design
D) two matched groups design