How do viruses spread?

The correct answer indicates that viruses can spread through vegetable propagation, which refers to the way in which plants reproduce using parts of themselves, such as cuttings or grafting. In this context, when a virus infects a plant, it can be passed on to new plants that are cultivated from infected plant material. For instance, if a cutting is taken from a virus-infected plant and is used to grow a new plant, this new plant can become infected as well.

Vegetable propagation is a common practice in gardening and agriculture, making it a significant method for the spread of viral pathogens. Some viruses are specific to certain plant species and can be persistently transmitted through this method, leading to outbreaks in new crops if appropriate precautions are not taken.

In contrast, the other methods mentioned, such as transmission exclusively by insect vectors or through soil transfer, do not encompass the broader ways in which viruses can spread, like through the propagation of infected plant tissues. Contamination from tools or rain can also contribute to spread but does not fully capture the essence of how viruses are often perpetuated through plant propagation.