Arrange the following in order from the smallest to largest level of organization: Peptide
Protein
Amino acid
Polypeptide

Amino acid, peptide, polypeptide, protein

Explanation:

Amino acids make up a peptide. A group of peptides form a polypeptide chain. A protein is a group of polypeptides.

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.