【单选题】Which one of the following statements is incorrect about Hodgkin lymphoma? A. Hodgkin lymphoma is characterized by the presence of Reed-Sternberg (RS) cells or the variants B. Hodgkin lymphoma always manifests systemic manifestations C. Hodgkin lymphoma always arises at a single lymph node and spreads characteristically in a stepwise fashion to contiguous lymph nodes D. Hodgkin lymphoma accounts for 80% of all lymphomas