Answer:
D. Use a web diagram with a general topic to create subtopics.
Step-by-step explanation:
The narrowing down of ideas is a crucial stage followed after the brainstorming of ideas as it assists in the selection of the best possible ideas and creating some innovative ideas after combining these ideas. This stage allows the researchers to specify the ideas as too broad ideas can be unmanageable and may create conflicting opinions and also difficult to research on every idea. Thus, a web diagram of a topic carrying different subtopics would give a concise and specified form to the researcher to focus his attention on. The first, second, third option indicates the generation of ideas that comprises the Brainstorming process and not the narrowing down of ideas. So, it's D.