The marker for B lymphocyte is:

Answer is A (CD19) : CD 19 is a marker fir B lymphocytes. Primarily B cell associated antigens include CD10 and CD19 to CD23 i.e. CD10, CD19, CD20, CD21, CD22, CD23 Primarily T cell associated antigens include CD1 to CD8 with the exception of CD6 i.e. C'D1, CD2, CD3, CD4, CD5, CD6, CD7, CD8. Primarily monocyte macrophage associated antigens CD13 to CD15 and CD33 i.e. CD13, CD14, CD15, CD33. Primarily NK cell associated antigens includeQ CD16 and CD56. (Do remember the antigens associated with NK cells. CD] 6 and CD56 being the primary ones, and also CD2 which is found expressed in a subset.Q)