Answer:
mail questionnaires
Step-by-step explanation:
Mail questionnaire: In research, the term mail questionnaire is defined as a form or type of questionnaire that is being mailed by the researcher to the targeted persons or group, that possesses a specific collection of questions on a few specific topic being asked to them and determined as a part of the survey or interview which is used for researching on that particular topic.
Advantage: Anonymity and confidentiality.
In the question above, Kathy's purpose is being best served by a mail questionnaire.