The best sentence that helps develop the idea expressed in paragraph 2 is:
"Thanks to this analysis, the researchers were able to narrow down their original list of 3,000 genes to 43 specific sequences that might have contributed to Lonesome George’s long, disease-free life."
This sentence provides direct evidence of how the researchers are using genetic analysis to gain insights into longevity, thereby supporting the idea that Lonesome George's genetic material can help understand what it takes to live a long life. It highlights the focus on specific genetic sequences that may be linked to his longevity, reinforcing the central theme of the research in the context of long-lived animals.