Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
Macrophages are large WBCs that can also swallow and destroy old and dying cells, bacteria, or viruses. Below, a macrophage is attacking and swallowing two particles, possibly disease-causing pathogens ( Figure below ). Macrophages also release chemical messages that cause the number of WBCs to increase.


Question: Macrophages, which can swallow and destroy old and dying cells, bacteria, or viruses, are large types of what cells?
white blood cells
White blood cells.