(A-D) Polysaccharide: Glycosidic bond. In polysaccharides,individual monosaccharide units are linked together by glycosidic bonds formed by dehydration synthesis.
$(b)$ Protein: Peptide bond. Proteins are polymers of amino acids,where the carboxyl group of one amino acid reacts with the amino group of another to form a peptide bond.
$(c)$ Fat: Ester bond. Fats (triglycerides) are formed by the esterification of glycerol with three fatty acid molecules,resulting in ester bonds.
$(d)$ Water: Hydrogen bond. Water molecules are held together by hydrogen bonds,which are weak electrostatic attractions between the partial positive charge of a hydrogen atom and the partial negative charge of an oxygen atom in adjacent molecules.