In a distribution of Z scores, the mean is always

Warrington & Shallice report a patient with a grossly defective STS (a digit span of two). This patient __________

a. had normal performance on the Brown-Peterson task b. had reasonable learning, memory, and comprehension c. had profound retrograde amnesia d. had no ability to store new long-term memories

"Do my results have any relevance to situations and populations not used in my experiment?"

This statement best represents an evaluation of A) extraneous variables B) statistical significance C) internal validity D) external validity