The methylene chloride solution is filtered through sodium sulfate to: a. Neutralize any acidic contamination

b. Neutralize any alkaline contamination

c. Dry the methylene chloride by removing water

d. Precipitate the caffeine from solution

C. Dry the methylene chloride by removing water

Explanation:

Anhydrous sodium sulfate is known for its high capacity to absorb water, for this reason it is widely used in laboratories as a drying agent.

Sodium sulfate is a neutral molecule so it cannot be used to neutralize and is very stable, so it is difficult to precipitate organic molecules.