Concept:Fiber crops are plants grown for their fibrous materials, which are used to make textiles, ropes, sacks, and similar products.
Explanation:Cotton, jute, and sisal are all cultivated for their fibres.
Cotton provides fibre from its seeds.
Jute and sisal provide fibre from their stems and leaves.
Onion, however, is grown mainly for its edible bulb and is classified as a vegetable crop.
Therefore, onion is not a fiber crop among the given options.
Answer:B. onion