The correct options are
B desalination
D reverse osmosis
Forward Osmosis is a normal osmosis process used in water purification, desalination process,etc. Here, a solution of higher solute concentration is allowed to flow with the process into a solution of lower concentration. It is a new field of research.
Water is separated from the unwanted particles using this process. Unlike reverse osmosis where a lot of outside pressure is applied, this process does not need external pressure source.
The osmosis process can actually be reversed if a pressure larger than the osmotic pressure be applied to the solution. This phenomenon has found uses in water purification, especially the desalination of sea water.