Correct Option
The correct option is Energy (Sunlight).
Explanation
Geomorphic processes are categorized based on the origin of the forces that drive them. Exogenic forces (external forces) operate on the Earth's surface, leading to the degradation (wearing down) and aggradation (filling up) of relief features. In contrast, Endogenic forces originate from within the Earth.
Detailed Analysis
- Energy (Sunlight) is Correct: Exogenic geomorphic processes-such as weathering, mass wasting, erosion, and deposition-derive their energy primarily from the atmosphere. The atmospheric circulation and the hydrological cycle, which power agents like wind, water, and glaciers, are driven by the ultimate energy from the Sun. Additionally, gradients created by tectonic factors and gravity aid these processes, but the primary energy input is solar.
- Options Radioactivity, Tidal friction, and Primordial heat are Incorrect: Radioactivity, tidal friction, and primordial heat are the primary sources of energy for Endogenic forces. These sources generate the geothermal gradients and internal heat flow responsible for volcanism, diastrophism, and plate tectonics.
Key Takeaway
Exogenic forces are driven by solar energy and gravitational gradients, whereas Endogenic forces are powered by the Earth's internal heat (radioactivity, primordial heat, and tidal friction).