Which of the following best describes the role of red blood cells?

The role of red blood cells is best described by their function in carrying oxygen throughout the body. Red blood cells, also known as erythrocytes, contain a protein called hemoglobin that binds to oxygen in the lungs and transports it to various tissues and organs. This process is crucial for maintaining the body’s metabolism and overall health, as oxygen is essential for producing energy in cells.

The other functions mentioned do not pertain to red blood cells. For instance, transporting immune cells is primarily the function of white blood cells, which play a key role in the immune response. Storing nutrients is not a function of red blood cells; rather, this is typically managed by organs such as the liver. Filtering blood is mainly carried out by the kidneys and the spleen, which remove waste products and dysfunctional cells. Therefore, the distinctive and vital role of red blood cells is their ability to carry oxygen, making this the correct answer.