Option 1: Glacial - Glacial processes are related to the movement of glaciers and the erosion and deposition of materials by ice. Pingos, however, are not directly associated with glacial processes.

Option 2: Peri-glacial - Peri-glacial processes occur in areas near the edges of glaciers or in regions influenced by cold climates. Pingos are a type of landform that is formed as a result of freezing and thawing of the ground in peri-glacial regions. They are typically conical mounds with an ice core.

Option 3: Aeolian - Aeolian processes involve the movement and deposition of sediments by wind. Pingos are not formed by wind action and are thus not associated with aeolian processes.

Option 4: Fluvial - Fluvial processes refer to the erosion, transportation, and sedimentation of materials by rivers. Pingos are not formed by the action of rivers and therefore are not associated with fluvial processes.

Therefore, the correct option is 2: Peri-glacial, as pingos are landforms associated with freezing and thawing processes in cold climate regions.