A typical example of landforms produced by marine erosion is a

Marine (coastal) processes can be divided into erosion and deposition. A stack is a classic landform produced by marine erosion.

Stacks form through a sequence of erosional stages:

1. Waves attack lines of weakness (joints and faults) in a headland through hydraulic action, abrasion, and corrosion.
2. A cave is carved into the headland.
3. If caves form on both sides and eventually meet, an arch is created.
4. Continued erosion widens the arch until its roof collapses, leaving an isolated column of rock standing in the sea - this is a stack.

The other options are landforms produced by deposition, not erosion. A spit is a ridge of sand or shingle extending from the coast, formed by longshore drift. A beach is an accumulation of sand, pebbles, or shingle deposited by wave action. A mud-flat is a low-lying area of fine sediment deposited in sheltered coastal zones such as estuaries.