In which one of the following does the host factor show bimodal incidence curve?

sometimes there may be two seperate peaks instead of one in the age incidence curve of a disease as in the case of HODGKIN&;S LYMPHOMA, LEUKEMIA,and female breast cancer .this phenomenon is known as bimodality.it indicates that thes tudy material is not homogenous and two distinct sets of causal factors may be operative eventhough the clinical and pathological manifestations of the disease are the same at all ages. ref:park&;s textbook,ed 22,pg no 65