Which one of the following is the cause of Corn smut?

Correct option is C

Corn smut is a plant disease caused by the pathogenic fungus Ustilago maydis that causes smut on maize and teosinte. The fungus is edible, and forms galls on all above-ground parts of corn species

Ustilago hordei (a) causes smut in barley, Pyricularia oryzae (b) causes rice blast, and Ustilago tritici (d) causes loose smut in wheat.