Smut of maize caused by

✅ Explanation: Common smut of maize is caused by the fungus Ustilago maydis. This fungus infects various parts of the maize plant, causing characteristic galls or tumors filled with black, powdery spores.

📌 Other Options Explanations:
-(a) Ustilago tritici: This fungus causes loose smut of wheat
-(c) Ustilago hordei: This fungus causes covered smut of barley