The answer is b.
Hope that helps :)
Bioluminescence is a chemical reaction that takes place in a living organism when the organism emits light. Bioluminescence doesn't consume or produce heat, hence it can be neither endothermic nor exothermic reaction. It emits a heatless light not heat.
For bioluminescence, it could be said that it is an exoenergetic reaction because it uses energy from a chemical reaction to produce light.
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