A researcher has developed a personality questionnaire to test for postpartum depression in women during the initial months after childbirth. The researcher has included the items "I feel sad and hopeless a lot" and "I react strongly to simple, everyday queries." As the questions are honest and transparent, the researcher runs the risk of women not admitting to feeling depressed and their passing off such feelings as tiredness. Which of the following methods has most likely been used by the researcher in developing the personality questionnaire?
A. A face valid method
B. A test-retest reliability method
C. An empirical method
D. An inter-rater reliability method