Why do contours on opposite sides of a stream have the same values?

• A. Contours are paired across drains
• B. Contours follow the stream closely
• C. Contours are drawn independently on each side
• D. Contours bend to avoid the stream

Answer: (A)

Contours mark lines of equal elevation on a map. In a valley carved by a stream, the land on both sides reaches the same elevations at corresponding locations. So the same contour value appears on opposite banks of the stream, effectively pairing across the drainage. This reflects that the terrain at a given height exists on both sides, even though the stream sits lower in the valley.

The other ideas don’t fit because contours aren’t drawn independently on each side, and they don’t simply ride along or dodge the stream; they reflect continuous elevation changes across the landscape, bending where the topography dictates.