Answer:
2
Explanation:
Number 2 is actually the sentence that is the main idea.
This is correct because the No. 2 sentence gives the overall information of what the passage is talking about. It actually captures the main information that the author is passing across. In fact, the sentence summarizes what the passage is all about.
No. 2 sentence reveals how the experiment brought remarkable changes in his body. The other sentences are supporting ideas.
