2. Please choose the answer from the following descriptions:1. a-Keratin is a protein which provides strength in connective tissue.2. Disulfide linkages are important for keratin structure.3. Gly residues are particularly abundant in collagen.4. L-isoleucine is an diastereomer of D-leucine.5. a-Keratin is a protein in which the polypeptides are mainly in the a-helix conformation.(A) 1 and 4 are incorrect.(B) 1 and 5 are incorrect.(C) 1, 2, and 3 are correct.(D) 3 and 4 are correct.(E) Only 2 and 5 are correct