The correct option is C Decantation
When an insoluble solid-liquid mixture is left undisturbed for sometime, the heavier component of the mixture settles down, leaving the lighter component on the top. This process is called sedimentation and the heavier component is the sediment.
In the case of most of the insoluble solid-liquid mixtures, the sediment is the insoluble solid. Once sedimentation is done, the clearer liquid can be carefully poured out leaving behind the sediment by a process called decantation.
Although sedimentation and decantation go hand-in-hand, both are different processes.