Which of the following pairs is incorrectly matched?

The correct answer is D. All three pairs are correctly matched, so the question has no incorrect pair.

• Thiamine (B1) and beriberi: Thiamine is a coenzyme in carbohydrate metabolism (as TPP). Its deficiency causes beriberi, which affects the nervous and cardiovascular systems. Polished rice was a classic source of this deficiency.
• Ascorbic acid and scurvy: Vitamin C is needed for hydroxylation of proline and lysine during collagen synthesis. Deficiency weakens connective tissue, causing spongy gums, bleeding and poor wound healing.
• Vitamin K and blood clotting: Vitamin K is needed for the gamma-carboxylation of clotting factors II, VII, IX and X, and of proteins C and S. Deficiency causes a bleeding tendency, including haemorrhagic disease of the newborn.

The core concept is micronutrient deficiency diseases, which fall under human physiology and nutrition in the General Science syllabus. For Mains GS-II, link this to public health and nutrition programmes such as fortification and the Poshan Abhiyaan.

Trap: Aspirants often assume a question with "none of the above" must hide a trick and start hunting for an error that isn't there. Check each pair against the exact deficiency disease and function. If all three hold, D is the answer.