Correct option (a) Loose smut of wheat
Explanation:
Fungal disease, lose strut of wheat spreads by seed and flowers. The causal organism of this disease is Ustilago fungus. it is an internal parasite. It has a dikaryotic mycelium which remains within the intercellular spaces of the host tissue. Tirs fungus infects the ovary of the host flower as a result of which the masses of teliospores or brand spores are formed in place of grains. Teliospores are not surrounded by, any wall hence, called loose smut.
