Correct answer: has a completely filled outermost shell
Atoms of the element with complete outermost shells are stable. So, in order to attain stability the atom either loses electrons or gains electrons to completely fill the outermost shell. The stable electronic configuration for the s and p-block elements is exhibited by the noble gases or the group 8 elements. All the unstable atoms try to attain the electronic configuration of the nearest noble gas with completely filled outermost shell.