Answer:

D

Explanation:

D - Open-Ended Questions are the most appropriate type of question for research as they allow for in-depth exploration of a topic and provide the opportunity for participants to express their thoughts and opinions in their own words. Open-ended questions typically begin with "why," "how," or "what" and are not limited to a specific set of responses, allowing for greater flexibility and depth of understanding. This type of question can provide valuable insights into complex issues and help to generate new ideas and perspectives.