What is a characteristic of the parent material (PM) found on top of a lake plain?

The characteristic of the parent material found on top of a lake plain is that it can have alluvium or glacial deposits. Lake plains are often formed from the sedimentation processes associated with lakes, where various sediments accumulate over time. These sediments can include alluvial deposits, which are materials deposited by rivers as they flow into the lake, and glacial deposits, which are remnants of glaciers that melted and contributed sediments to the area.

This variability in parent material signifies that lake plains are not uniform and can be influenced by different geological processes. The presence of alluvium relates to the dynamics of water flow in and out of the lake, while glacial deposits can indicate past glacial activity in the area.

The other choices may not accurately represent the diversity found in these environments. While lacustrine sediments, which are deposited directly by lake processes, are common, they do not exclusively define the parent material of a lake plain. Significant volcanic material is not typically associated with lake plains unless there is a specific volcanic activity in the region, and being primarily sandy does not encompass the full range of sediment types that can be found. Therefore, the correct understanding of parent material on a lake plain encompasses a broader range of geological influences, including alluvium