4 deletion
Explanation:
deletion is a type of genetic mutation involving the removal of a base pair
If there's options, I assume mutation?
1. One reason is extinctions happen because of some kind of change in the environment where a life form lives. While some species can adapt to the changes, others die, and if enough die, the species becomes extinct. These are some of the biggest factors in the extinctions of particular species. 2. Contaminants in the environment, such as pesticides.
Organisms with hard parts such as a shell,or bones are much more likely to become fossilized than animals with soft parts like a worms.