The correct answer is NaCl and H2O.
HCl or hydrochloric acid refers to a strong acid, which ionizes entirely in aqueous solution to generate chloride anions and hydrogen cations. NaOH or sodium hydroxide refers to a strong base, which is when dissolved in water, ionizes completely to produce hydroxide anions and sodium cations.
When the pellets of sodium hydroxide are added to the HCl solution, the NaOH will ionize completely, and the hydroxide anions and the hydrogen cations will neutralize each other to generate water. The other product of the reaction is NaCl.
The balanced chemical equation is:
NaOH (s) + HCl (aq) → NaCl (aq) + H2O (l)