Final answer:
Dr. Brown's findings that different methods for the same trait are highly correlated and that methods for different traits are not demonstrate convergent validity and discriminant validity, respectively.
Step-by-step explanation:
Dr. Brown's observation that results from different methods used to assess the same trait are highly correlated demonstrates convergent validity. Convergent validity refers to the degree to which two measures of constructs that theoretically should be related, are in fact related. On the other hand, the observation that results from different methods used to assess different traits are not significantly correlated demonstrates discriminant validity. Discriminant validity, also known as divergent validity, is the extent to which a construct is truly distinct from other constructs by empirical standards. Therefore, the correct answer to the student's question is C) Convergent validity and Discriminant validity.