Which of the following best describes the function of the spleen?

The spleen plays a crucial role in the body's immune response and in the maintenance of blood health, which is why filtering blood and recycling iron is the best description of its function. The spleen filters the blood, identifying and removing old or damaged red blood cells. This process is vital because the body relies on healthy red blood cells for transporting oxygen. Along with filtering, the spleen also recycles iron from the hemoglobin of these cells, allowing the body to reuse this essential mineral in the production of new red blood cells.

The other options describe functions associated with different organs and processes in the body. Storing bile is a function of the gallbladder, while producing hormones is primarily carried out by various glands, such as the pituitary or thyroid glands. Secretion of digestive enzymes is performed by the pancreas and the salivary glands, which aid in breaking down food during digestion. Thus, option B accurately describes a primary and important function of the spleen.