What does column chromatography primarily rely on for separation?

Column chromatography primarily relies on gravity and molecular interactions to achieve separation. In this technique, a mixture is passed through a column filled with a stationary phase, which can be a solid or a liquid. As the mixture moves through the column, different substances within the mixture interact with the stationary phase to varying degrees based on their chemical properties such as polarity, size, or charge.

The differences in interactions cause some components to move faster and others to move slower, resulting in their separation along the column. Gravity assists in the flow of solvents and mixtures through the column, further facilitating the separation process. The combination of molecular interactions and the force of gravity is fundamental to the mechanism of column chromatography, making option C the correct answer.