The answer would be B, photosynthesis.
Using the process of elimination, the answer is easy to find.
Polysynthesis - The act or process of combining many separate elements into a whole (Free Dictionary)
Amino-acid Synthesis - No definition, but this is clearly not the answer as amino acid has nothing to do with carbon dioxide or oxygen.
Amino-acid Production - This doesn't work for the same reason as the last one. Amino acid is irrelevant.
Therefore, the answer is photosynthesis.
