What causes a delta to form?ResponsesA Deltas form at the mouth of a river when wind deposits sand.Deltas form at the mouth of a river when wind deposits sand.B Deltas form on the bank of a river when a glaciers move past.Deltas form on the bank of a river when a glaciers move past.C Deltas form at the mouth of a river when water slows down and deposits sediment.Deltas form at the mouth of a river when water slows down and deposits sediment.D Deltas form on the banks of a river when water slows down and deposits sediment.

The correct answer is C. Deltas form at the mouth of a river when water slows down and deposits sediment. Here's a step-by-step explanation:

1. As a river flows, it picks up sediment from the river bed, banks, and surrounding landscape.
2. The river carries this sediment downstream towards its mouth, which is where the river meets a body of water such as a sea or a lake.
3. When the river reaches its mouth, the speed of the water flow decreases. This is because the river is no longer confined to its narrow channel and spreads out.
4. As the water slows down, it can't carry as much sediment. The sediment is heavier than the water, so it falls to the bottom.
5. Over time, more and more sediment is deposited at the mouth of the river. This builds up and forms a delta.
6. The delta continues to grow as long as more sediment is deposited than is washed away by waves, tides, or currents.