Question

why is the jellyfish red?
it absorbs light for energy
scientists dont know
to scare predators
it uses the color to camouflage

Explanation:

Jellyfish do not photosynthesize (so they don't absorb light for energy like plants). There is no evidence that red color in jellyfish is for scaring predators or camouflage. And in fact, the exact reason for the red color in some jellyfish is not fully understood by scientists.

Answer:

Scientists don't know.