How do white blood cells differ from red blood cells?

White blood cells (WBCs) differ from red blood cells (RBCs) primarily in their function and mobility. The correct answer highlights that white blood cells have the unique ability to leave blood vessels to reach tissues where infections or inflammation are present. This characteristic is vital for the immune response, enabling WBCs to combat pathogens effectively and facilitate healing processes.

Red blood cells, on the other hand, primarily function to transport oxygen from the lungs to the body tissues and return carbon dioxide from the tissues back to the lungs. They do this without having the ability to exit blood vessels. While both types of cells are crucial for maintaining health, it is the WBCs' mobility and ability to migrate out of the bloodstream that distinguishes them in their role in the immune system.

The other options present facts that do not accurately reflect the key differences between the two cell types. White blood cells do not contain hemoglobin like red blood cells do; they are not necessarily longer-lived than red blood cells; and, generally speaking, white blood cells are larger than red blood cells. These distinctions reinforce the importance of the migration capability of WBCs in response to infection.