I believe the correct answer is d.
How is controlling wide spread/contagious diseases made difficult by the fact that it spreads through multiple species of animals?
(is it still too complicated?)
Answer:
Because it contains carbonic acid
Explanation:
Carbonic acid is made from dissolving carbon dioxide in water. Since carbon dioxide is exhaled in the lungs, and the exhaled air is moist due to the presence of water molecules from the alveoli, then the carbon dioxide gas will be dissolved in the exhaled air’s moisture rendering it slightly acidic.
More than 3.6 billion years!
resupplying the ground water