• Capsaicin Principle: Pungency (heat/spiciness) in chilli peppers (Capsicum annuum and Capsicum frutescens) is caused by capsaicin (8-methyl-N-vanillyl-6-nonenamide) and related capsaicinoids, which activate heat-sensing TRPV1 receptors on sensory nerve endings.
• Capsanthin & Capsorubin: The principal carotenoid pigments responsible for the intense red color of ripe dried chilli fruits, possessing no pungency.
• Chalcone: An aromatic ketone flavonoid intermediate. (Correct answer: Option 2)

• Chemical Nature of Sinigrin:
• Sinigrin (allylglucosinolate / potassium 2-(sulfooxy)but-3-enethioate) is a secondary plant metabolite abundant in seeds of Brassica nigra (black mustard) and Brassicaceae.
• Chemically, sinigrin is classified as an $S$-glycoside (glucosinolate) consisting of a glucose molecule bound via a $\beta$-thioglucoside linkage to a sulfonated oxime moiety.
• Upon tissue rupture, the endogenous enzyme myrosinase hydrolyzes sinigrin to yield volatile, pungent allyl isothiocyanate.
• Conclusion: Sinigrin is chemically classified as a Glycoside (Option 3).

Correct option: (3) Glycoside

• Classification of Enterodiol:
• Enterodiol is a mammalian phytoestrogenic compound chemically categorized under the Lignans group (diphenolic compounds derived from phenylalanine via dimerization of cinnamic alcohol derivatives).
• In animal and human metabolism, intestinal microflora convert plant dietary lignans (such as secoisolariciresinol diglucoside from flaxseed) into enterodiol and enterolactone.
• Conclusion: Enterodiol belongs to the Lignan class (Option 3).

Correct option: (3) Lignan