Answer:
A. Methane
Explanation:
Methane is a gas not a solid. Every other answer choice is a solid.
I think it is A because they can just destroy it but D is finding something natural to kill it off but it is GM so it wouldn't help so A
1. Photosynthesis produces two products, glucose and oxygen.
2. Respiration will take the products of photosynthesis and convert them into carbon dioxide and water.
The answer would be false because some organisms have a possibility at failing other things.