Natural resources underground are resources that are found beneath the surface of the Earth. These resources are formed over millions of years through natural processes and are essential for various human activities and industries. The correct answer, option 'C', refers to natural resources that are located underground.

Here is a detailed explanation of the different types of resources mentioned in the question:

1. Artificial resources:
- Artificial resources are human-made resources that are created through various processes.
- These resources are not naturally occurring and are produced to fulfill specific needs.
- Examples of artificial resources include buildings, roads, bridges, and factories.

2. Future resources:
- Future resources refer to resources that are not currently being utilized or exploited but have the potential to be valuable in the future.
- These resources may include new sources of energy, advanced technologies, and undiscovered natural resources.
- As technology and scientific knowledge advance, certain resources that were previously inaccessible or unknown may become future resources.

3. Natural resources underground:
- Natural resources underground are resources that are located beneath the Earth's surface.
- These resources include minerals, such as gold, silver, iron, copper, and uranium.
- Coal and petroleum are also natural resources that are found underground.
- These resources are formed through geological processes over long periods of time.
- They are extracted through mining and drilling techniques to be used for various purposes, including energy production, manufacturing, and construction.

4. Natural resources on Earth's surface:
- While the question does not mention any specific examples of natural resources on the Earth's surface, it is important to note that these resources also play a crucial role in human activities.
- Surface resources include forests, water bodies, fertile soil, and renewable energy sources like sunlight and wind.
- These resources support diverse ecosystems, provide habitats for wildlife, and are utilized for agriculture, recreation, and renewable energy generation.

In conclusion, the correct answer 'C' refers to natural resources that are located underground. These resources, such as minerals, coal, and petroleum, are formed through natural processes and play a significant role in various industries and human activities.

Natural resources underground