the answer is A. because it is right
It is a structural carbohydrate which forms their exoskeleton. exoskeleton is the external skeleton that supports and protects an animal's body.
The right answer is C
I will explain the law of conservation of energy by photosynthesis:
The conservation principle states that the energy of an isolated system (chlorophyll) can not vary.
On the other hand, if the system is not isolated (it is in the nature, exposed to the sun), that is to say if it can exchange with the outside, (the chlorophyll will absorb the photons put by the Sun). Thus the system transforms this absorbed energy into another form (glucose in the case of photosynthesis).
I think they are harmful but never beneficial or neutral