In a replacement (double displacement) reaction between barium nitrate (Ba(NO3)2) and sodium sulfate (Na2SO4), the products are barium sulfate (BaSO4) and sodium nitrate (NaNO3).
The balanced equation for the reaction is:
\[ \text{Ba(NO}_3\text{)}_2 + \text{Na}_2\text{SO}_4 \rightarrow \text{BaSO}_4 + 2\text{NaNO}_3 \]
Therefore, the correct answer among your options is:
2NaNO3 + BaSO4