New findings suggest that brainy card games such as contract bridge may temporarily  raise production of a key blood cell including in fighting off illness. After 90 minutes of play, bridge players had increased levels of immune  cells, according to the research reported last week. A researcher, Diamond, studied bridge players from a women's bridge club. She chose bridge players because the game includes skills stimulating  a part of the brain called the dorsolateral cortex. Earlier animal research suggests that this part of the brain may play a role in the immune system. The findings are based on blood samples drawn from 12 women players. Their blood samples showed a rise in levels of white blood cells called T cells after they played bridge for 90 minutes. T cells are produced by the thymus gland  and used by the immune system against diseases. The T cell count jumped significantly in eight of the bridge players, and slightly in the other four. The findings contribute to the field of neuroimmunology , whose name reflects the fact that the nervous system and the immune system are not considered separate and isolated  systems. What isn't clear is whether the help to the immune system from an activity like contract bridge is lasting or temporary. It is also not clear whether the increase in T cells could finally be targeted against special illnesses. A T cell is   _   cell.
a brain a white blood a red blood a kind of dangerous blood
Question: New findings suggest that brainy card games such as contract bridge may temporarily  raise production of a key blood cell including in fighting off illness. After 90 minutes of play, bridge players had increased levels of immune  cells, according to the research reported last week. A researcher, Diamond, studied bridge players from a women's bridge club. She chose bridge players because the game includes skills stimulating  a part of the brain called the dorsolateral cortex. Earlier animal research suggests that this part of the brain may play a role in the immune system. The findings are based on blood samples drawn from 12 women players. Their blood samples showed a rise in levels of white blood cells called T cells after they played bridge for 90 minutes. T cells are produced by the thymus gland  and used by the immune system against diseases. The T cell count jumped significantly in eight of the bridge players, and slightly in the other four. The findings contribute to the field of neuroimmunology , whose name reflects the fact that the nervous system and the immune system are not considered separate and isolated  systems. What isn't clear is whether the help to the immune system from an activity like contract bridge is lasting or temporary. It is also not clear whether the increase in T cells could finally be targeted against special illnesses. A T cell is   _   cell.
A. a brain
B. a white blood
C. a red blood
D. a kind of dangerous blood
Answer: