The human immunodeficiency virus (HIV) often infects and destroys CD4 T cells. These CD4 cells are one of many kinds of white blood cells that are an important part of the immune system. The most common danger related to the destruction of CD4 T cell is-

A. an increase in the risk of high blood pressure.
B. an increase in threat of diseases caused by microorganisms and viruses.
C. a decrease in the flow of blood to vital organs.
D. a decrease in the amount of oxygen being transported to tissues.