Question

which biome is characterized by permafrost? desert taiga tropical rainforest tundra

Explanation:

Permafrost is a layer of permanently frozen soil. The tundra biome has this characteristic due to its extremely cold climate. Other biomes like desert (hot and dry), taiga (coniferous forests, colder but not with permafrost as a key feature), and tropical rainforest (warm and wet) do not have permafrost as a defining trait.

Answer:

Tundra