The correct answer is option 1 - Vitamin A. Precursors are substances that are converted into active forms or components in the body. In the case of Vitamin A, the precursor is /2-carotene.

/2-carotene is a pigment found in various fruits and vegetables, particularly orange and green ones like carrots, sweet potatoes, spinach, and kale. When consumed, /2-carotene is converted into Vitamin A in the body through a process called enzymatic cleavage.

Vitamin A is essential for maintaining healthy vision, supporting immune function, and promoting proper growth and development. It also plays a role in the health of the skin and mucous membranes.

Vitamin C (option 2) is obtained from citrus fruits and is important for immune function, collagen synthesis, and antioxidant protection. However, its precursor is not /2-carotene.

Vitamin D (option 3) is synthesized in the skin when it is exposed to sunlight or obtained from certain foods. It is crucial for maintaining strong bones and regulating calcium and phosphorus levels.

Vitamin K (option 4) is necessary for blood clotting and bone health. Its main dietary sources are leafy green vegetables and vegetable oils.

Therefore, the correct answer is indeed