The element that is a key component of the thyroid hormones T₃ and T₄ is: MCQ with Answer and Explanation

Explanation:
Vitamin K is essential for the synthesis of clotting factors (II, VII, IX, X) in the liver. Deficiency leads to prolonged clotting time and excessive bleeding. Vitamin A is for vision, C for collagen (scurvy causes bleeding gums but not clotting defect), D for bones. Newborns receive vitamin K injection to prevent hemorrhagic disease. Green leafy vegetables are rich sources.

Explanation:
Vitamin E (tocopherol) is a fat-soluble antioxidant that protects cell membranes from lipid peroxidation. Vitamin C is water-soluble antioxidant, A is for vision, D for calcium.

Explanation:
Beta-carotene is a provitamin A carotenoid, giving orange color; the body can convert it to retinol. Lycopene is red (tomato), xanthophyll yellow, chlorophyll green. Carotenoids are accessory pigments in photosynthesis.