Notch is a receptor protein displayed on the surface of certain cells in developing fruit fly embryos. Notch's ligand is a membrane-bound protein called Delta that is displayed on the surface of adjacent cells, When Notch is activated by its ligand, the intracellular tail of the Notch protein becomes separated from the rest of the protein. This allows the intracellular tail to move to the cell's nucleus and alter the expression of specific genes. Which of the following statements best explains Delta's role in regulating cell communication through the Notch signaling pathway? (A) Delta transmits a chemical signal to all the cells of a developing embryo. (B) Delta allows the cells of a developing embryo to communicate without making direct contact. (C) Delta restricts cell communication to short distances within a developing embryo. (D) Delta determines which cells in a developing embryo express the gene that encodes the Notch protein.