To accurately answer how paragraph 4 refines the central idea, I would need to see the text of paragraph 4. However, based on the response options you've provided, it seems that the paragraph could refine the central idea in one of the following ways:
- Detailing Benefits: If it gives more specific information on how studies will positively impact humans, it would be the first response.
- Providing Facts/Statistics: If it includes data that supports the main argument, it would align with the second response.
- Background Information: If it offers context that enhances understanding of the central idea, it matches with the third response.
- Restating the Idea: If it paraphrases the main point while introducing new insights, it corresponds with the fourth response.
Without the actual text, I can't definitively select one of these options. Please provide the paragraph, and I’ll be happy to assist further!