The right answer is Questionnaire. Questionnaire and interview can be confusing since both require a need to answer questions. A questionnaire requires a set of pre-made questions to be asked to the interviewee while an interview can ask questions on the spot or to continue a thought that was tackled on a previous question.
An interview can last longer than the use of a questionnaire due to follow-up questions and more clarifications. In a questionnaire, you just need to follow the questions you listed as these are relevant to your research. Usually, questionnaires are well-thought-out than the questions asked in interviews as questions in questionnaires are filtered to be the most appropriate and essential to research.