The correct answer is option 3: glaciofluvial deposits. An esker is a type of landform that is created by glacial meltwater flowing through or underneath a glacier. As the water melts, it carries with it sediment and debris from the glacier. This sediment is then deposited in the form of a long and sinuous ridge, which is known as an esker.

Option 1, mechanical weathering, refers to the physical breakdown of rocks into smaller pieces due to forces like temperature changes, frost wedging, or root growth. While mechanical weathering can shape the landscape, it does not directly create eskers.

Option 2, river action, involves the erosion and deposition of sediment by rivers. While rivers can have an impact on the formation of landforms, eskers are specifically formed by glacial meltwater and are not associated with rivers.

Option 4, aeolian deposits, refers to the deposition of sediment by wind. While wind can shape the landscape in various ways, it does not directly contribute to the formation of eskers.

Therefore, option 3, glaciofluvial deposits, is the correct answer as it accurately describes the process through which eskers are formed.