The most effective method of controlling or preventing viral diseases in plants ...

The question is asking for the most effective method of controlling or preventing viral diseases in plants.

Viral diseases are caused by viruses, which are tiny infectious agents that can attack and damage plants. To control or prevent viral diseases, the most effective method is to plant resistant varieties.

Resistant varieties are plant varieties that have been specifically bred to be resistant to certain viruses. This means that even if the viruses are present in the environment, the resistant plants will not get infected or will have milder symptoms. By planting resistant varieties, farmers can greatly reduce the risk of viral diseases in their crops.

Spraying crops regularly, burning affected crops, practising crop rotation, and treating seeds with chemicals may be useful for managing other types of plant diseases, but they are not as effective in controlling viral diseases. Viruses are not easily killed by chemicals, and burning affected crops or rotating crops may not completely eliminate the viruses from the environment.

Therefore, the correct answer is option A: planting resistant varieties. This is the most effective method for controlling or preventing viral diseases in plants.

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