Which of the Following Questions Is/are Important in Critically Appraising

Which of the following questions is/are important in critically appraising surveys?

A) Was the information collected in a valid, unbiased manner?
B) Were the survey respondents representative of the target population?
C) Were the conclusions warranted in light of the design logic, the type of data analysis employed, and the findings of that analysis?
D) All of the above.