A Training Stimulus of a Red Square Inside of a Yellow

Multiple Choice

A training stimulus of a red square inside of a yellow circle was used in a keypeck experiment with pigeons.In a follow-up experiment, one trained pigeon was found to respond more to a red square than a yellow circle.Another trained pigeon responded more to the yellow circle.This demonstrates that

A) stimulus control did not develop in the initial training.
B) stimulus control developed only in the subject responding more to the red square.
C) stimulus control developed only in the subject responding more to the yellow circle.
D) stimulus control can vary from subject to subject.