Answer:
D. Surveys allow students to answer the questions in private and assure the confidentiality of their responses.
Step-by-step explanation:
If the students are forced to directly answer the question regarding the sex and drug use in person, they will fear the negative social impact that might harm the perception that their peers have toward them. This will make them become more likely to lie and give false information.
Surveys eliminate this problem and allow the researchers to obtain more accurate information.