Which of the fungi produces toxins in crop plants?

The correct option/answer is both (b) and (c).

Let's analyze the fungi listed in the options and their ability to produce toxins in crop plants:

1. Aspergillus (b): Species of the genus Aspergillus, particularly Aspergillus flavus and Aspergillus parasiticus, are well-known to produce highly toxic compounds called aflatoxins. These toxins commonly contaminate crop plants, especially grains, seeds, and nuts (such as corn, peanuts, and tree nuts), presenting severe health risks to humans and livestock.
2. Penicillium (c): Species of the genus Penicillium produce various mycotoxins, such as ochratoxin A and patulin. Ochratoxin A can contaminate cereal crops (like wheat, barley, and rye), while patulin is commonly found in rotting apples and fruit-derived products.
3. Colletotrichum (a): While Colletotrichum species are notorious plant pathogens that cause anthracnose (a disease characterized by dark, sunken lesions on leaves, stems, and fruits), they are primarily known for causing physical damage and cellular necrosis rather than producing significant systemic mycotoxins that contaminate crops for consumption.

Therefore, both Aspergillus and Penicillium are major toxin-producing fungi in crop plants, making "both (b) and (c)" the correct choice.