Which landform can form when sediments deposit at a river mouth?

Correct answer: Delta

The direct answer is C, Delta. A river carries small pieces of soil, sand and rock called sediments. Near its mouth, where the river enters a sea or lake, the water usually slows down. Slow water cannot carry as much material, so the sediments settle and collect. Over time, this deposited material may form a roughly triangular or fan-shaped delta. Option A, Valley, is a low area between hills or mountains and is not formed specifically by deposition at a river mouth. Option B, Waterfall, forms where water drops suddenly over a steep or resistant rock step; it is not a mouth-deposition landform. Option C is correct because a delta is formed by river deposition at or near the mouth. Option D, Pass, is a route or low gap through hills or mountains, not a deposit made at a river mouth. Remember: river mouth plus deposited sediments means delta. The exact shape may vary, but the process described clearly points to a delta.