The name of the landform remaining after a sea arch collapses is a sea stack.
The correct answer is a "sea stack." To obtain this answer, you could start by understanding what a sea arch is. A sea arch is a natural archway formed by the erosion of a sea cave. Next, you would need to know what happens when a sea arch collapses. When a sea arch collapses, the top part of the arch crumbles and falls into the water, leaving behind a freestanding pillar of rock. This pillar is known as a sea stack. Therefore, the correct answer to the question is a "sea stack."
