Question

Which is one way that waves erode coastlines?

Back-and-forth movement loosens sediment and rock.
Large rocks are picked up and deposited in new areas.
Continuous impacts build up sediment and rock.
Loose sediment is picked up and blown to other locations.

Answer 1

Back-and-forth movement loosens sediment and rock.

Waves erode coasts mainly by hydraulic action and abrasion — the repeated motion and impact of water and sediment loosens and removes material.