Answer :
It would be letter D - A mutation occurs in one copy of the original gene.
Mutation is the changing of a structure of a gene that can be passed down to the next generations. It is the source of all evolution. As mutation progress through time, it leads to evolution.
Mutation is the changing of a structure of a gene that can be passed down to the next generations. It is the source of all evolution. As mutation progress through time, it leads to evolution.