Carl Has Frequent Infections And, After Testing, Has Been Diagnosed

Multiple Choice

Carl has frequent infections and, after testing, has been diagnosed with a genetic form of agammaglobulinemia (meaning no gamma globulins in the blood) . Why would this condition result in difficulty fighting off infections?

A) His B cells can't make antibodies, so he has no humoral immune response.
B) His T cells over-react, resulting in activation of autoantibodies.
C) His macrophages are overproducing cytokines, making the immune response ineffective.
D) He is unable to produce T cells, so he has no cellular immune response.