Match List - I with List - II.

	List-I		List-II
(a)	Protein	(i)	C = C double bonds
(b)	Unsaturated fatty acid	(ii)	Phosphodiester bonds
(c)	Nucleic acid	(iii)	Glycosidic bonds
(d)	Polysaccharide	(iv)	Peptide bonds

To solve this matching question, let us analyze the macromolecules and features listed in List-I and find their corresponding linkages or characteristics in List-II:

(a) Proteins:
Proteins are polymers of amino acids. Amino acids are linked together by covalent bonds called peptide bonds, which form between the carboxyl group of one amino acid and the amino group of the next. Therefore, (a) matches with (iv).

(b) Unsaturated fatty acids:
Fatty acids consist of hydrocarbon chains. Saturated fatty acids contain only single bonds between carbon atoms, while unsaturated fatty acids contain one or more carbon-carbon (C = C) double bonds in their hydrocarbon chain. Therefore, (b) matches with (i).

(c) Nucleic acids:
Nucleic acids (like DNA and RNA) are polymers of nucleotides. The nucleotides are joined together by phosphodiester bonds, specifically between the 3'-carbon atom of one sugar molecule and the 5'-carbon atom of another. Therefore, (c) matches with (ii).

(d) Polysaccharides:
Polysaccharides are complex carbohydrates composed of long chains of monosaccharide (sugar) units. These monosaccharide units are linked together by covalent bonds known as glycosidic bonds. Therefore, (d) matches with (iii).

Combining these matches, we get:
• (a) - (iv)
• (b) - (i)
• (c) - (ii)
• (d) - (iii)

Thus, the correct option is (a) - (iv) , (b) - (i) , (c) - (ii) , (d) - (iii).