Adsorption is a mechanical process of soil that_______________.

Adsorption is a key mechanism in soil science that involves the adhesion of ions, molecules, or particles from a liquid (like water) onto the surface of a solid (in this case, soil particles). This process is crucial for understanding how pollutants, nutrients, and other substances interact with soil.

Option B highlights that adsorption will occur in water characterized by high hardness and a neutral or slightly acidic pH. This is accurate because water with high hardness typically contains elevated levels of calcium, magnesium, and other minerals, which can enhance the adsorption capacity of soil by promoting interactions between soil particles and the adsorbate. Additionally, a neutral to slightly acidic pH is favorable for many soil types as it can facilitate the absorption of nutrients and contaminants, thereby affecting the efficiency of adsorption.

In contrast, the other options refer to processes or characteristics that are not directly related to the mechanism of adsorption itself. Understanding these distinctions helps clarify why adsorption plays a vital role in soil and water management, especially in on-site sewage facilities where the retention and treatment of contaminants is essential.