A CELL WALL because the other three appear in different types of cells
Not sure what the choices are but a biotic factor is anything living.
<span>Methyl groups
</span>DNA<span> methylation is a process by which </span>methyl groups<span> are added to the </span>DNA<span> molecule. Methylation can change the activity of a </span>DNA<span> segment without changing the sequence.</span>
