You are presented with the quiz "What causes growth?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "cell division often causes growth" and "cancer is an uncontrolled cell division". So, what's the best answer to the question?

Choices:
1). Cancer.
2). bushes
3). Roundworms
4). bamboo
5). hormones
6). Earthworms
7). collagen
8). Proteins
The answer is:
1).