Ergot disease of cumbu (pearl millet) is caused by

Correct option is B

Ergot disease affects inflorescence of pearl millet.
It produces honey-dew stage followed by sclerotia formation.
The causal organism is Claviceps fusiformis. Other options cause downy mildew, rust or leaf spots.
Hence, Claviceps fusiformis is the correct pathogen. Therefore, option (b) is correct.