Question

1. when a sea arch erodes and falls in, a ______ is formed.

sea stack
headland
beach
sea cliff

Explanation:

A sea stack forms when the rock beneath a sea arch erodes completely, causing the arch to collapse and leave an isolated rock column. Headlands are original rocky outcrops, beaches are sediment deposits, and sea cliffs are steep coastal rock faces, none of which result from a collapsed sea arch.

Answer:

sea stack