Professor Swanson Developed an Index of Marital Happiness

Multiple Choice

Professor Swanson developed an index of marital happiness.Several items in Swanson's questionnaire were not a part of the index (i.e. ,"How many serious quarrels or arguments have you had with your spouse in the past year?") Swanson compared the index scores of marital happiness with these questions.Swanson was doing:

A) index validation.
B) item analysis.
C) external validation.
D) index validation and item analysis.
E) index validation and external validation.