The correct answer is: A. Inversely proportional to the scale of the map.
A contour interval is the vertical distance between two adjacent contour lines on a topographic map. The contour interval is inversely proportional to the scale of the map. This means that the smaller the scale of the map, the larger the contour interval. For example, a map with a scale of 1:25,000 will have a contour interval of 10 meters, while a map with a scale of 1:50,000 will have a contour interval of 20 meters.
The contour interval is used to represent the relief of the land on a topographic map. The closer the contour lines are together, the steeper the slope of the land. The farther apart the contour lines are, the more gentle the slope of the land.
The contour interval is also used to measure the elevation of points on the land. The elevation of a point is the vertical distance above sea level. The elevation of a point can be determined by finding the contour line that passes through the point.
The contour interval is an important tool for understanding the topography of an area. It can be used to plan hiking and biking trails, to identify areas of potential flooding, and to assess the risk of landslides.
Here is a brief explanation of each option:
- Option A: Inversely proportional to the scale of the map. This is the correct answer. The smaller the scale of the map, the larger the contour interval.
- Option B: Directly proportional to the flatness of ground. This is not the correct answer. The contour interval is not affected by the flatness of the ground.
- Option C: Larger for accurate works. This is not the correct answer. The contour interval is not affected by the accuracy of the map.
- Option D: Larger if the time available is more. This is not the correct answer. The contour interval is not affected by the amount of time available to create the map.