I'm not sure what you're asking, but if you're looking for a word to describe this change its "mutation"
D. before cells without a true nucleus
It’s the first choice because the C at the end does not pair with anything, it was an extra pair that was made
B, The bacteria that live in the intestine of a rabbit. Biotic creature are things that are living, breathing, and need food/water to live. Hope this helps!! & have a great day!!!