PLEASE HELP ME ANSWER I MADE IT WORTH 40 POINTS

How does gene duplication allow new genes to develop over many generations? Select two answer choices.

A) If the original gene becomes non-functional because of a mutation, it will be selected against, and could be deleted because it accumulates further mutations over time to eventually become a non-functional gene.
B) In organisms with duplicated genes, the original gene and its function is maintained while allowing mutations to occur in the duplicated gene that can lead to new variations.
C) In organisms with duplicated genes, the original gene and its function is deleted while allowing mutations to occur in the duplicated gene that can lead to new variations.
D) If the duplicated gene becomes non-functional because of a mutation, it will not be selected against and could accumulate further mutations over time to eventually become a gene with new functions.