19) 13, Br3, and Cl3 exist, but F3 does not. What is the best explanation for this? A. The central F atom cannot expand octet, while I, Br, and Cl atoms can. B. The central F atom cannot adopt negative formal charges, while I, Br, and Cl atoms can. C. The central F atom cannot form double bonds, while I, Br, and Cl atoms can. D. The central F atom would have to expand octet, while I, Br, and Cl atoms would not. E. The central F atom fill the 2d subshell, while the central I, Br, and Cl atoms do not. 5