Which of the following is a fungus commonly seen on plants?

• A. Virus
• B. Nematode
• C. Bacteria
• D. Powdery mildew

Answer: (D)

Powdery mildew is a type of fungus that commonly affects plants, and it appears as a white, powdery coating on leaves, stems, and sometimes flowers, especially in humid, moderate-temperature conditions. This makes it the correct choice because it is a fungal pathogen, unlike the other options. A virus is an infectious particle that invades plant cells and often causes mosaics or deformities; a nematode is a tiny worm that damages roots or other tissues; bacteria are single-celled organisms that can cause spots, rot, or wilting. The powdery mildew growth and its biology clearly identify it as the plant fungus among those possibilities.