C.
Biotic mean alive, so we can cut off the first 2 easily. Aquatic birds eat frogs, so that one is safe for now. A decrease in something parasitic usually helps the population, so D is out too. The only one left is C.
Answer:
Polymer
Explanation:
polymer: A relatively large molecule consisting of a chain or network of many identical or similar monomers chemically bonded to each other. monomer: A relatively small molecule that can form covalent bonds with other molecules of this type to form a polymer.
