(NH4)2SO4 is a salt of strong acid and weak base, on hydrolysis it ill produce H+ion. This will increase the acidity of soil. $\begin{aligned}
& \left(\mathrm{NH}_4\right)_2 \mathrm{SO}_4 \longrightarrow 2 \mathrm{NH}_4^{+}+\mathrm{SO}_4^{2-} \
& \mathrm{NH}_4^{+}+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{NH}_4 \mathrm{OH}+\mathrm{H}^{+}
\end{aligned}$ Hence, (D) is correct answer.