The correct option is Kayals.
Explanation
The Malabar coast, situated along the southwestern edge of the Indian peninsula (primarily in Kerala), possesses distinct physiographic features. Among these, the presence of backwaters is a defining characteristic that distinguishes it from other coastal regions.
Option Analysis
- Kayals (Correct): The Malabar coast is famous for its backwaters, locally known as 'Kayals'. These are shallow lagoons or lakes lying parallel to the coast, separated from the sea by sandbars. They form a distinct feature of the Kerala coast and are extensively used for fishing, inland navigation, and tourism. The famous Nehru Trophy Boat Race is held in Punnamada Kayal.
- Barchans (Incorrect): These are crescent-shaped sand dunes found in the Indian Desert region (Thar Desert), characterized by their specific wind-driven formation. They are not coastal features.
- Karewas (Incorrect): These are thick deposits of glacial clay and other materials embedded with moraines, found in the Kashmir Himalayas. They are renowned for saffron (Zafran) cultivation.
- Doabs (Incorrect): A Doab is a tract of land lying between two converging rivers. This feature is characteristic of the Northern Plains (e.g., the Ganges-Yamuna Doab) and is not a coastal formation.
Key Takeaway: Kayals are the backwaters characteristic of the Malabar coast in Kerala, serving as vital resources for fishing, transport, and tourism.