Red sea is an example of:

The Red Sea fits C) Axial trough. It is a narrow, elongated depression along a zone of continental rifting, where the Arabian plate is pulling away from the African plate. Its floor is underlain by new oceanic crust, and the basin has been widening since roughly 25-30 million years ago. The central depression along the rift axis is what geomorphology calls an axial trough.

• A) Volcanic valley: Not a standard landform category. Volcanic activity is present in the region, but that does not define the Red Sea's structure.
• B) Eroded valley: Eroded valleys are carved by rivers or glaciers over time. The Red Sea is a tectonic depression, not an erosional feature.
• D) U-shaped valley: This is a glacial valley, found in Himalayan, Alpine or Kashmir-type terrain. The Red Sea has no glacial origin.

The concept links to plate tectonics and sea-floor spreading, which the syllabus covers under geomorphology and the Earth's interior. For Mains, the same rifting process explains the East African Rift and the Afar triple junction.

Trap: Candidates pick the 'valley' option that sounds like a river or glacier landform. Ask first whether the feature is tectonic, erosional or glacial.