The correct option is The sub soil is permanently frozen (permafrost)..
Explanation
The Tundra Climate (designated as ET in the Köppen classification) is a type of Polar Climate found in high latitudes. It is characterized by extremely low temperatures, a lack of true summer, and a distinct treeless landscape.
Statement-wise Analysis:
- Statement It has a very short duration of daylight in summer. is Incorrect. Tundra regions are located in high latitudes (mostly beyond the Arctic Circle). Consequently, they experience very long daylight hours during the summer, often resulting in the "Midnight Sun" phenomenon where the sun does not set for several days or weeks.
- Statement It supports large trees and dense forests. is Incorrect. The environmental conditions in the Tundra-specifically the short growing season and strong winds-prevent the growth of large trees. Vegetation is limited to low-lying plants such as mosses, lichens, sedges, and dwarf shrubs.
- Statement The sub soil is permanently frozen (permafrost). is Correct. A defining feature of the Tundra is permafrost, a layer of subsoil that remains permanently frozen throughout the year. Only the top few inches of soil thaw during the brief summer, creating marshy and swampy surface conditions because the water cannot drain through the frozen subsoil.
- Statement It is found only in the Southern Hemisphere. is Incorrect. The Tundra climate is most extensively developed in the Northern Hemisphere (e.g., Northern Canada, Alaska, Russia, Scandinavia). In the Southern Hemisphere, the corresponding latitudes are largely occupied by oceans, limiting Tundra regions to small areas like the Antarctic Peninsula and some sub-Antarctic islands.
Key Takeaway: The Tundra Climate is strictly defined by the presence of permafrost, a treeless landscape, and a thermal regime where the warmest month has an average temperature between 0°C and 10°C.