How many of the following pairs of secondary metabolites and their categories are correctly matched? (I) Pigments : Carotenoids (II) Drugs : Ricin (III) Alkaloids : Codeine (IV) Polymeric substances : Gums

Step-by-step solution

According to the NCERT classification of secondary metabolites: Pair (I) is correct because carotenoids and anthocyanins are pigments. Pair (II) is incorrect because ricin is a toxin, whereas drugs include vinblastin and curcumin. Pair (III) is correct because codeine and morphine are alkaloids. Pair (IV) is correct because gums, rubber, and cellulose are polymeric substances. Therefore, exactly three pairs are correctly matched. Answer: Only three