The correct option is D Sphagnum
Species of Sphagnum provide peat. Peat is used as fuel and as packing material for trans-shipment of living material due to their capacity to hold water.
Peat is mainly an accumulation of partially decayed vegetation or organic matter and Sphagnum accumulations can store wate. In Sphagnum since both living and dead plants can hold large quantities of water and living matter (like meat eggs) for long distance transport inside their cells hence, it is responsible for peat formation.
Sphagnum is a genus of mosses, commonly known as peat moss. Peat is an accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands. As Sphagnum moss grows, it can slowly spread into drier conditions, forming larger peatlands.
Hence the correct option is D.