Professor Myth Asked Respondents Whether or Not They Had Ever

Multiple Choice

Professor Myth asked respondents whether or not they had ever been divorced. One year later Professor Myth asked respondents the same question. Myth found that with repeated applications of the measure different responses were obtained for the same subject. This means that the measuring instrument was​

A) ​unreliable.
B) ​invalid.
C) ​unreliable or the value on the variable had changed.
D) ​lacking in face validity.