The correct option is B Least genetic diversity
In crop lands genetically uniform seeds are planted under uniform conditions. Monocultural agriculture thus causes low crop diversity, especially when the seeds are mass-produced or when plants (such as grafted fruit trees and banana plants) are cloned. So least genetic diversity is a characteristic of crop lands.
Soil organisms and weeds are present in all types of ecosystems including cropland ecosystem.
Ecological succession is the process by which the structure of a biological community evolves over time.