Explanation:
Ozone, or 03,has two major resonance structures that contribute equally to the overall hybird structure of the molecule. The two structures are equivalent from the stability standpoint, each having a positive and a negative formal charge placed on two of the oxygen atoms.
The correct response would be 3. The alkaline earth metals would tend to lose its valence electrons, in this case 2 of them at different energy levels, to form the same respective ion, which is +2.