Concept:Fungal diseases of stored grain are caused by fungi that grow on grains during storage, especially under warm and moist conditions.
Explanation:When grains are stored with high moisture, fungal spores germinate and multiply rapidly.
Mould is one of the most common fungal infections that spoil stored grains.
Streak and mosaic are not fungal in origin; they are caused by viruses.
Damping off is a fungal disease of seedlings, not of stored grains.
Since the question specifically asks for a fungal disease of stored grain, mould is the correct choice.
Hence, the other options are not suitable.
Answer:A. mould