Which of the Following Is Not Essential in Maintaining Confidentiality

Multiple Choice

Which of the following is not essential in maintaining confidentiality in field or survey interviews?

A) remove names and addresses from data-collection forms
B) keep a master identification file linking numbers to names so that at a future date, data can be corrected where necessary
C) put the master file on the computer so that you do not leave paper copies of the file laying around
D) only legitimate researchers should have access to the master file