A mountain top becomes smoother over time due to

Erosion such as rain and wind, as well as landslides due to flooding. Some mountains tectonic plates shift, also gravity is a big factor.

Explanation:

There are many, many factors that cause mountains to change with time, but ultimately they can be broken down into the factors that decrease the mountain altitude versus those that increase it. The height of a mountain is the result of the competition between the forces of uplift through deformation, and the forces of attrition or weathering and transport by gravity (always downhill!) Gravity then takes these particles downhill. If it rains, the rocks and sands get carried by water downstream. Also when it rains, the rocks dissolve a little bit and the rivers wash the cations carried in solution into the ocean.

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i would say b probably

answer; i believe that the correct answer is culture based resources;