Which of the following indicates a low WBC count?

Leukopenia is a term used to describe a decreased white blood cell (WBC) count, indicating a low level of circulating white blood cells in the body. A low WBC count can make a person more susceptible to infections, as white blood cells are essential for the immune response and fighting off pathogens.

Leukocytosis, on the other hand, refers to an increased WBC count, which is often a response to infection, inflammation, or other health conditions. Thrombocytosis involves an elevated platelet count, not white blood cells, while neutrophilia indicates an increase in neutrophils, a type of white blood cell, typically in response to infection or stress. Therefore, leukopenia directly correlates to a low WBC count, making it the correct answer in this scenario.