I'm pretty sure the answer is "C "or "ion", because since lithium is losing one of its electrons, and since lithium usually has three electrons, then the result has to be a ion. An ion is an atom or molecule that is different from the actual element because of a gain or loss of one or more electrons.
It couldn't be a molecule, because a molecule is a group of atoms bonded together.
It couldn't be a compound, because there is only one element losing an electron, not two elements combining together.
It couldn't be atom, because an atom is part of a molecule. It is the smallest part of an element.
HOPE THIS HELPS! :)