Solodization refers to the removal of . . . . . . . . from the exchange sites

Answer: Option C

Solodization also known as dealkalization is the process of gradual removal of sodium ions from the exchange sites.
It is nothing but the leaching of sodium from the upper soil horizons to remove alkalis. The sodium ions from the exchange sites can be removed by adding Gypsum to the soil. This process involves the dispersion of clay.