Which of the following terms best describes areas that are not agriculturally productive?

The term that best describes areas that are not agriculturally productive is "marginal areas." These regions typically possess less favorable conditions for farming compared to more productive lands. This can be due to factors such as poor soil quality, extreme weather conditions, steep terrain, or limited access to water. Marginal areas may still support some form of agriculture, but it is often less viable and less sustainable over time.

In contrast, fertile regions refer to lands that are rich in nutrients and capable of supporting robust agricultural activities. Prime farmland indicates areas specifically recognized for their high productivity and ability to yield significant agricultural outputs. Industrial zones are areas designated for economic activities related to manufacturing and services, and they are not primarily focused on agriculture at all. Therefore, marginal areas are the most appropriate choice to describe those lands that lack productive agricultural capacity.