Option 1: Wheat is not categorized as a millet. Wheat is a cereal grain and belongs to the wheat family, which includes other varieties such as durum, spelt, and emmer. Millets, on the other hand, are a group of small-seeded grains that belong to the Poaceae family.

Option 2: Rice is not categorized as a millet either. Rice is a staple food for many people around the world and is widely cultivated and consumed. It belongs to the grass species Oryza sativa, which is different from the millet family.

Option 3: Sorghum is the correct answer. Sorghum is a type of millet and is widely consumed in many parts of the world as a staple food. It is a versatile grain that can be used for human consumption, animal feed, and the production of biofuels. Sorghum belongs to the Poaceae family and is known for its drought-resistant properties.

Option 4: Maize, also known as corn, is not classified as a millet. Maize belongs to the grass species Zea mays and is a staple food in many countries. It is not part of the millet family.

In conclusion, among the given options