You are presented with the quiz "How is survival ensured around hydrothermal vents?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "organisms cluster around hydrothermal vents in the ocean floor" and "to survive, some organisms living near hydrothermal vents have formed close associations". So, what's the best answer to the question?

Choose from: a. heat produced b. Eating a lot c. Reproducing quickly d. biological diversity e. vegetation f. Being in a cluster g. Staying far apart h. hydrate their cells
The answer is:
f.