The correct answer is B. 5 m.
A contour interval is the vertical distance between two adjacent contour lines on a topographic map. The contour interval is chosen based on the scale of the map and the relief of the land. A smaller contour interval will show more detail, but it will also be more difficult to read. A larger contour interval will be easier to read, but it will not show as much detail.
For a map with a scale of 1:10000, the suitable contour interval is 5 m. This is because the scale of the map is 1:10000, which means that every 1 cm on the map corresponds to an actual distance of 10000 cm, or 100 m. A contour interval of 5 m would result in contour lines that are 2 cm apart on the map, which is a good spacing for a map of this scale.
If the contour interval were 2 m, the contour lines would be 1 cm apart on the map, which would be too close together and make the map difficult to read. If the contour interval were 10 m, the contour lines would be 10 cm apart on the map, which would be too far apart and not show enough detail.
Therefore, the suitable contour interval for a map with a scale of 1:10000 is 5 m.