What shows that resources are not only natural things?

Correct answer: Knowledge skill and technology are also resources

The direct answer is A. A resource is not defined only by being found in nature. Something becomes a resource when people have the knowledge, skill, technology, and need to identify and use it for a useful purpose. Step by step: natural materials may exist; human knowledge discovers their uses; skills and technology help extract or transform them; usefulness and value increase. Thus knowledge, skill, and technology are human-related resources. Option A is correct because human capacity and technology help turn materials into usable resources and also have value themselves. Option B is wrong because rivers are only one type of natural resource, not the whole category. Option C is wrong because mountains are another natural resource or landform, but not all resources. Option D is wrong because soil is important, especially for farming, but it is only one resource. The full idea includes natural, human-made, and human resources. Memory cue: nature provides possibilities; people and technology make them useful.