How does gene duplication contribute to the formation of gene families?

• A. Gene duplication restricts genetic variation and prevents the formation of new gene families.
• B. Gene duplication only occurs in non-coding regions and does not affect gene families.
• C. Gene duplication is unrelated to the formation of gene families.
• D. Gene duplication allows for multiple copies of a gene to evolve independently, potentially leading to new functions.

Answer: (D)