Step 1: Understanding land cover in remote sensing.
- Land cover refers to the physical material covering Earth's surface, such as forests, water bodies, and urban areas.
Step 2: Explanation of incorrect options.
- Physical condition of vegetation b.: Falls under land use, not land cover.
- Topography c.: Refers to elevation, not land cover.
- Soil cover on land d.: A component of land cover but not the full definition.
Step 3: Selecting the correct option.
Since land cover refers to the physical condition of the ground surface, the correct answer is a. Physical condition of ground surface.