What is Hairy Cell Leukemia? How does it appear on the PBS?

a) Clonal proliferation of mature B cells with hair-like projections; Circulating hairy cells in PBS
b) Excessive production of eosinophils; Presence of Auer rods in PBS
c) Proliferation of T lymphocytes; Smudge cells in PBS
d) Clonal proliferation of plasma cells; Rouleaux formation in PBS