At a point during a cell's development, it begins to differentiate. How does differentiation occur? A. A developing cell's function is determined by the number of organelles that are contained in the cell. B. Certain genes are turned on and others are turned off; this action produces adult cells that are specialized. C. As a cell matures, genes that are not necessary to its function are ejected out of the cell through active transport. D. The number of chromosomes in the cell is reduced by half; this action triggers the specialization of the cell.