What is the process through which reverse osmosis separates water from contaminants?

Reverse osmosis is a water purification process that effectively separates water from contaminants through the use of a semi-permeable membrane. In this process, pressure is applied to overcome the natural osmotic pressure, pushing water molecules through the membrane while leaving behind larger particles, such as salts, bacteria, and other impurities.

Filtration, as it relates to reverse osmosis, specifically refers to the method by which contaminants are removed from water using the membrane. Unlike traditional filtration systems that rely on mesh or porous materials, reverse osmosis can filter out very fine particles and dissolved substances, providing a high level of purification.

Other processes like evaporation involve converting water into vapor, which is not applicable for separating contaminants in the way reverse osmosis does. Diffusion refers to the movement of particles from an area of higher concentration to one of lower concentration, but it does not utilize a membrane or pressure to accomplish separation, nor does it specifically target contaminants as reverse osmosis does. Direct osmosis involves water movement across a semi-permeable membrane but in the direction to equalize solute concentrations, rather than to purify water from contaminants.

Thus, the correct choice highlights the importance of filtration in the reverse osmosis process, emphasizing its role in achieving clean