Correct Option: A. Planting resistant varieties Explanation of the Correct Answer:

1. Understanding Viral Diseases in Plants: Viral diseases in plants are caused by viruses that can lead to significant crop losses. These viruses can be transmitted through various means, including insect vectors (like aphids), contaminated tools, or infected seeds. Once a plant is infected, it can be challenging to control the spread of the virus.
2. Planting Resistant Varieties: The most effective method to control or prevent viral diseases is by planting resistant varieties. This means selecting and cultivating plant varieties that have been genetically bred or selected for their ability to resist specific viruses. These resistant varieties can either prevent the virus from entering the plant or limit its ability to reproduce and spread within the plant.
3. Genetic Resistance: Resistant varieties often possess specific genes that confer resistance to certain viruses. For example, some tomato varieties have been bred to resist the Tomato spotted wilt virus (TSWV). By planting these varieties, farmers can significantly reduce the incidence of viral infections in their crops.
4. Long-term Solution: Planting resistant varieties is a sustainable and long-term solution. Once established, these varieties can continue to provide protection over multiple growing seasons, reducing the need for chemical interventions and minimizing the impact on the environment.

Why the Other Options are Weaker: B. Spraying crops regularly: - While spraying crops with pesticides can help control insect vectors that transmit viruses, it does not directly prevent viral infections. Moreover, this method can lead to pesticide resistance in pests and may harm beneficial insects and the environment. It is also a reactive approach rather than a proactive one, as it does not address the root cause of the problem. C. Burning affected crops: - Burning affected crops can help eliminate visible symptoms of viral infections and reduce the immediate spread of the virus. However, this method is not a comprehensive solution. It does not prevent new infections from occurring in the future, especially if resistant varieties are not planted. Additionally, burning can lead to soil degradation and loss of organic matter. D. Practising crop rotation: - Crop rotation can help manage soil health and reduce pest populations, but it is not specifically effective against viral diseases. Many viruses can survive in the soil or on non-host plants, meaning that simply rotating crops may not prevent viral infections. Furthermore, if susceptible varieties are planted in subsequent seasons, the risk of viral outbreaks remains. Summary of Key Points:

• Planting resistant varieties is the most effective method for controlling viral diseases in plants, providing long-term protection.
• Spraying crops is a reactive measure that does not prevent infections and can harm beneficial organisms.
• Burning affected crops eliminates visible symptoms but does not prevent future infections and can degrade soil health.
• Practising crop rotation helps with soil health but is not specifically effective against viruses, as they can persist in the environment.

By focusing on resistant varieties, farmers can enhance their crop resilience and reduce the impact of viral diseases on agricultural productivity.