19. What reason is given for the stability of C□O, N□N, and O□O bonds, compared to the instability of Si□Si, P□P, and S□S bonds? (A)Their metallic character varies greatly. (B) There are large differences in their abilities to form strong pi bonds. (C) There are large differences in their ionization energies. (D)There are large differences in their electronegativities. (E) none of these