Question

an atom has been reduced when it:
pushes electrons
shares electrons
loses electrons
gains electrons

Explanation:

In a redox reaction, reduction is defined as the gain of electrons. When an atom gains electrons, its oxidation state decreases. Pushing electrons is not a standard term in redox definitions. Sharing electrons is more related to covalent bonding rather than redox reactions. Losing electrons is oxidation.

Answer:

gains electrons