Dr. Liu conducted an experiment showing that manipulated levels of frustration increased levels of aggression in kids. Dr. Liu observed the same basic results for (a) kids of different ages, (b) girls versus boys, and (c) kids of three different ethnic backgrounds. What do points a, b, and c mean? A) it supports the internal validity of her findings
B) it supports the external validity of her findings
C) it supports both the internal and the external validity of her findings