The correct concept shown by the structure of water is that in water, each oxygen atom shares two electrons and each hydrogen atom shares one electron. Option 1.
This image refers to the concept of covalent bonding. In the water molecule shown, each hydrogen atom shares one electron with the oxygen atom, and the oxygen atom shares two of its electrons - one with each hydrogen atom.
This forms two covalent bonds, one between the oxygen atom and each hydrogen atom.
The other statements are not accurate descriptions of the structure of water. For example, in a water molecule, the oxygen atom does not have a complete outer energy level, and neither do the hydrogen atoms.
Also, in water, the oxygen atom does not lose two electrons, and the hydrogen atoms do not gain one electron - they share electrons through covalent bonding.
Lastly, neither hydrogen nor oxygen atoms have a complete outer energy level in a water molecule.