Technically A and B, but A is more true, so it is the 'correct' answer.
The answer to this question would be: vitamin
Some bacteria can produce vitamin K2 in the intestine. Other bacteria also able to change vitamin K1 into vitamin K2. But the amount produced is not much, so human still need to fulfill it from the diet. Vitamin K has a role in calcium regulation and in blood clotting pathway.
A mutation may result change in the way you look, you could lose sight, could be born with some genetic issues.
It is called peristalsis movement.
A proper habitat and Preferences different specialized niches
