Humans are social animals so conversation is necessary to keep a human away being lonely which can lead to compression then death
Blue colors dominate the visible light output of very hot stars (with much additional radiation in the ultraviolet). On the other hand, cool stars emit most of their visible light energy at red wavelengths (with more radiation coming off in the infrared).
Sunlight would be an answer because you are talking about the lower depths of the ocean meaning the bottom of the ocean, and the farther away you get from the surface the less sunlight
Eight / ocho 8
thats the answer for 8