Tulsi plant has medicinal values due to the presence of which of the following?

The correct answer is C) Phenols and Flavonoids. Tulsi (Ocimum sanctum) owes much of its medicinal activity to phenolic compounds such as eugenol and rosmarinic acid, and to flavonoids such as orientin and vicenin. These are the compounds behind its antioxidant, anti-inflammatory and antimicrobial effects that Ayurveda has used for centuries.

• A) Inorganic acid: Mineral acids like HCl or H2SO4 are not plant constituents with therapeutic value. They are corrosive and have no role here.
• B) Organic acid: Plants do contain organic acids, and rosmarinic acid is one. But the question asks for the class that defines tulsi's medicinal value, and that is the phenolic and flavonoid group.
• D) Ethanol: Ethanol is a solvent used to extract tulsi's compounds. It is not the active constituent of the plant.

This is basic phytochemistry, but it links to the Mains theme of traditional knowledge, AYUSH, and bio-prospecting under GS III, where the question is how indigenous plant knowledge is validated scientifically.

Trap: Aspirants pick "organic acid" because it sounds like a chemistry term that fits a plant. Remember that the question asks for the active class the exam expects, not any compound that happens to be present.