homework help ? Human Biology an Disease ...

Aplastic anemia. This rare form of anemia results when the number stem cells in red bone marrow decrease. This could be due to exposure of toxic chemicals, including chemotherapy, or due to an autoimmune response in which leukocytes target and remove stem cells in the bone marrow. Aplastic anemia results in a measurable change to which variable?
A. heart rate decreases
B. stroke volume decreases
C. hematocrit decreases
D. tidal volume decreases