A unique horticultural product from Bihar is:

Makhana (fox nuts)
Kiwi fruit
Saffron
Dragon fruit

The correct answer is: a) Makhana (fox nuts).

Makhana is a unique horticultural product from Bihar. It is a type of water chestnut that is grown in the state. Makhana is a popular snack food and is also used in a variety of dishes. It is a good source of protein, fiber, and carbohydrates.

Kiwi fruit is a fruit that is native to China. It is a green fruit with a fuzzy skin. Kiwi fruit is a good source of vitamin C and fiber.

Saffron is a spice that is derived from the stigmas of the saffron crocus. It is a very expensive spice and is used in a variety of dishes. Saffron is a good source of antioxidants.

Dragon fruit is a fruit that is native to Mexico and Central America. It is a red fruit with a white flesh. Dragon fruit is a good source of vitamin C and fiber.

Makhana is a unique horticultural product from Bihar because it is a type of water chestnut that is grown in the state. Makhana is a popular snack food and is also used in a variety of dishes. It is a good source of protein, fiber, and carbohydrates. Kiwi fruit, saffron, and dragon fruit are not unique horticultural products from Bihar.