Which of the following statements on lymphoma is not true ?

• A. Several types of non Hodgkin's lymphoma (NHL) may have a leukemic phase
• B. In general follicular(nodular) NHL has worse prognosis compared to diffuse NHL
• C. A single classification system for Hodgkin's disease (HD) is almost universally accepted
• D. HD more often tends to remain localized to a single group of lymph nodes and spreads by contiguity