For the statements A, B and D, the correct explanation is, A. A tripeptide contains of 3 amino acid linked by two peptide linkage. B. A pentapeptide contains 5 amino acids linked by four peptide linkages. D. In case of cellulose, β-D-glucose units are joined by the glycosidic linkage between C-1 of one glucose and C-4 of the next glucose unit.