What is the purpose of this excerpt from the article "What Is GIS?"? GIS also can be used for complex modeling to answer a wide range of "what if" and ecosystem simulation questions. These may be cartographic models designed to document the co-occurrence or interrelationship of multiple data layers or they may be hypothetical research models designed to mimic natural ecological systems. Similarly, modeling with GIS can be used to predict the impacts that one set of parameters will have on another. For example, wetlands, soils, hydrography, climatology and elevation data can be combined to model flooding within a river system. Upstream changes in land use within the same system can be modeled to determine the potential impact of conversion of a forested floodplain to residential development or to agriculture. As a result, both natural system responses to storm events and the impact of human land use decisions can be assessed prior to the proposed action. to warn readers about the hazards of diminishing wetlands to inform readers about the multiple uses of GIS to explain the workings of the ecosystem simulations to instruct readers about proper use of GIS resources
In my opinion, the correct answer is B. to inform readers about the multiple uses of GIS. The excerpt doesn't talk about the ecosystem as such, but proposes a few ways to use GIS for modeling and answering many questions about the ecosystem. So, it focuses on the tool, and not the ecosystem itself.
