A Patient Has a White Cell Count of 12 $\kappa$ Light Chains Present on Their Surface

A patient has a white cell count of 12.6 *10⁹/L, hematocrit of 28%, and platelet count of 27*10⁹/L. Examination of a Wright-stained blood film reveals that almost all of the white cells in peripheral blood are blasts; the bone marrow is hypercellular with very little fat and is packed with blasts. Flow cytometry is performed on the peripheral blood cells, and a large cluster of cells is present that mark with CD20 and have monoclonal $\kappa$ light chains present on their surface. This patient has a:

A) Myeloid leukemia
B) Mature B-cell malignancy
C) Reactive B-cell hyperplasia
D) Mature T-cell malignancy