Combining aqueous solutions of Bal2 and Na2SO4 affords a precipitate of BaSO4. Which ion(s) is/are spectator ions in the reaction? \text { A. } \mathrm{Ba}^{2+} \text { and } \mathrm{SO}_{4}^{2}

\text { B. } \mathrm{SO}_{4}{ }^{2-} \text { and } \mathrm{I} \text { C. } \mathrm{Na}^{+} \text {only } \text { D. } \mathrm{Ba}^{2+} \text { only } \text { E. } \mathrm{Na}^{+} \text {and } \mathrm{I}