A Patient Has Come to You for a Second Opinion

A patient has come to you for a second opinion. "I have these mysterious lumps in my right armpit," he says, "The other doctor says we may have to remove them. What do you think?" You notice red scratches on the patient's right arm. "You must have a new kitten. Cat scratch disease, from the bacterium Bartonella ," you say, "And we certainly won't remove those lumps, they are really important! Those are your..."

A) "spleen, where hematopoietic stem cells produce lymphoid and myeloid progenitors."
B) "lymph nodes, where T-cell receptor genes are rearranged as T cells mature."
C) "lymph nodes, where naive B and T cells encounter antigens and become activated."
D) "thymus glands, where naive B and T cells encounter antigens and become activated."