Explanation:

 The correct answer of the above question is that there is Filtration at molecular level in RO. The reverse osmosis water purifier protects us from the harmful effects of lead, heavy metals, chlorine, chemical contaminants, pathogens, bacteria, E. Colt, cyst, Giardia, Cryptosporidium, taste, odors, and sediments. Osmosis: When two liquids of different concentration are separated by a semipermeable membrane, the fluid has a tendency to move from low to high solute concentrations for chemical potential equilibrium. Reverse Osmosis: Reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a semipermeable membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. The membranes used for reverse osmosis have a dense layer in the polymer matrix. In most cases, the membrane is designed to allow only water to pass through this dense layer, while preventing the passage of solutes (such as salt inns). This process requires that a high pressure he exerted on the high concentration side of the membrane so that the natural osmotic pressure is overcome. This process is best known for its use in desalination (removing the salt and other minerals from sea water to get fresh water), but since the early 1970s it has also been used to purify fresh water for medical, industrial, and domestic applications.