In Order to Collect Enough Participants to Satisfy Your Adviser's

In order to collect enough participants to satisfy your adviser's suggestion, you tell all your housemates to fill out your questionnaire. This is problematic because:

A) your housemates likely feel compelled to take part so are not volunteers.
B) your housemates are likely more like you than the members of the general population.
C) you are in a financial contract through your shared landlord so ethics committees cannot approve either financial transactions among housemates or research time commitments.
D) All of these.