Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth's surface.
C is what i think is correct.
The correct answer is C.
Amino acids consist of two different parts, the nitrogen-containing portion (NH2 group, dor the amino acid) and the carbon skeleton, containing the COOH, the acidic part. Two amino acids form bonds between their amino and acidic parts and form peptides that build up to proteins.