Final answer:
The correct option is a) Resistance to pests and diseases.
The benefit of maintaining potato plant diversity is primarily resistance to pests and diseases. This genetic diversity is essential for breeding new varieties and contributes to the resiliency of crops against catastrophic events.
Step-by-step explanation:
The related benefit of maintaining the diversity of potato plants, with different varieties known to thrive at different altitudes, is primarily resistance to pests and diseases. This diversity is a fundamental aspect of agricultural diversity, ensuring that in the event of an outbreak of pest or disease, not all plants would be susceptible. For instance, during the Irish potato famine, the lack of crop diversity led to widespread devastation when the single variety grown became susceptible to potato blight.
Genetic diversity within crop species is crucial because it facilitates the breeding of new varieties that can withstand evolving pathogens. Additionally, the availability of diverse potato varieties is significant because it extends the range of usable land for cultivation and enhances the ability to withstand catastrophic events, as diverse varieties of a crop surrounded by a diverse ecosystem are more likely to survive.