Which of the following describes a key feature of white blood cells?

White blood cells, also known as leukocytes, are a vital component of the immune system, and one of their distinguishing characteristics is their multi-lobed nucleus. This feature is particularly notable in a type of white blood cell called neutrophils, which often have their nucleus divided into three to five lobes, connected by thin strands of nuclear material. This structure not only allows for greater flexibility as the cells navigate through tissues but also aids in their function of phagocytosis, where they engulf and digest pathogens.

In contrast, some other options describe features that are not characteristic of white blood cells. For example, red blood cells are known for their concave shape and high levels of hemoglobin, which are crucial for their role in oxygen transport. White blood cells, however, do not carry out this function and typically contain little to no hemoglobin. Additionally, while some white blood cells do have organelles, they generally have different structures and functions compared to red blood cells, which ultimately lack a nucleus and most organelles to maximize space for hemoglobin. Thus, the multi-lobed nucleus is a defining and critical feature that enables white blood cells to perform their immune functions efficiently.