Explanation:

- Option 1, six: Halogens do not have six electrons in their outer shells. This is characteristic of members of the oxygen family, not halogens.

- Option 2, eight: Elements with eight electrons in their outer shells are noble gases. Halogens have fewer electrons and are one group away in the periodic table.

- Option 3, five: This is incorrect for halogens. Five outer electrons are typical for elements in the nitrogen group.

- Option 4, seven: Halogens have seven electrons in their outermost shells. This makes them reactive as they need one more electron to achieve a stable configuration.