question: Q:A 3-year-old boy goes camping with his parents in the Appalachian mountains of Western North Carolina. While on the hiking trip, he is exposed to an antigen. After the exposure, this antigen is phagocytosed by a CD4+ T helper cell and is presented on an MHC class II molecule. This CD4+ T helper cell encounters a B cell in the lymph node shown in the image below. The mature B cell proliferates and differentiates to produce antibodies to target this antigen. In which of the following numbered sections of the lymph node does this B cell differentiation and proliferation most likely occur?? 
  {'A': '1', 'B': '2', 'C': '3', 'D': '4', 'E': '5'},