What role does the spleen play in the body?

The spleen plays a crucial role in blood filtration within the body. It is responsible for filtering and removing old or damaged red blood cells, as well as pathogens and debris from the blood. The spleen contains white blood cells that help fight infections, making it an essential organ for the immune system. By filtering the blood, the spleen also helps to recycle iron and other components from red blood cells, which can be reused for the production of new cells. This filtration process contributes significantly to maintaining the body's overall health and immune response.

In contrast, the other options do not accurately describe the spleen's functions. Regulating blood pressure involves the cardiovascular system and the kidneys, while digestive enzyme production occurs in the pancreas and other organs of the gastrointestinal tract. Nutrient absorption is primarily conducted by the intestines, where digested food is absorbed into the bloodstream. Thus, the correct answer highlights the spleen's specific and vital role in blood filtration and immune defense.