Peach leaf curl is caused by a

Correct option is A

Peach leaf curl is a destructive disease of peach caused by a fungal pathogen that attacks young leaves and shoots. The disease leads to severe leaf curling, thickening, blistering, and discoloration, which affects plant growth. Infection occurs under cool and moist climatic conditions, especially during early spring. Hence, peach leaf curl is caused by fungi.
Information booster: Peach leaf curl disease is caused by Taphrina deformans, which belongs to the class Ascomycetes. The disease mainly affects newly emerging leaves, reducing photosynthesis and overall tree vigor. Proper fungicidal sprays before bud burst are effective in controlling the disease. Neglecting control measures may lead to poor yield and reduced fruit quality.
Why other options are incorrect: (b) Bacteria usually cause wilts, cankers, or soft rots, not leaf curl symptoms. (c) Virus diseases commonly produce mosaic or mottling symptoms rather than thickened leaves. (d) Viroid infections are rare and not associated with peach leaf curl disease.