Certain districts in Bihar specialize in the production of specific crops, such as:

Mangoes and Litchis
Makhana (fox nuts)
Vegetables
All of the above

The correct answer is: d) All of the above.

Bihar is a state in eastern India. It is the third-largest state in India by population, after Uttar Pradesh and Maharashtra. The state is known for its fertile land and its production of a variety of crops.

Mangoes and litchis are two of the most popular fruits grown in Bihar. Mangoes are a major export crop for the state, and litchis are a popular fruit in India and other parts of the world.

Makhana (fox nuts) are a type of aquatic plant that is grown in Bihar. They are a popular snack food in India, and they are also used in a variety of dishes.

Vegetables are also grown in Bihar. Some of the most popular vegetables grown in the state include potatoes, tomatoes, onions, and eggplants.

Bihar is a major agricultural state, and it produces a variety of crops. The state is known for its mangoes, litchis, makhana, and vegetables.