DNA is not a stimulus that a living thing might sense and respond to.
If a biotic factor were hungry, it would respond by seeking food. If a biotic factor heard a sudden and unexpected sound, it would respond by looking to identify what the sound was or where it came from. If a biotic factor was exposed to a sudden bright light, they would react by squinting their eyes to better see what the light was.
DNA on the other hand cannot be sensed or responded to. It is an internal function that’s automatic and cannot be altered.
C is not a stimulus that a living thing might sense and respond to.