Answer:
B) The surface layer of permafrost thaws in summer.
Explanation:
Permafrost is frozen ground or frozen soil. It is a landform in which the ground remains frozen for over a long period of time usually more than two years. Permafrosts are usually found in high latitude regions. For a permafrost to form, the temperature must remain considerably below freezing point.
The surface layer of a permafrost is bounded by the permafrost table and below it lies the active layer. During summer when temperature rises above freezing point, this layer thaws. In winter times, the surface layer remains frozen.