Arrange the following cells in the order of their development. CD34+ cells are developed in the bone marrow. They travel to the thymus and differentiate into lymphoid progenitor cells. They progress through DN1 cells, DN2 cells, and DN3 cells during TCR rearrangement. Successful receptor expression triggers differentiation into DN4 cells before selection differentiates them into DP cells. These cells exit the thymus never to return. The options are: pro B cells, pre B cells, plasma cells, hematopoietic cells, SP cells, CD4 T cells.