In the Following Proof, Which Justification Is Correct for Line

Multiple Choice

In the following proof, which justification is correct for line 4? $\begin{array}{llcc} \text {(1) Mnn \( \cdot \sim \) Enr } && \text { Premise } \\ \text {(2) \( (\exists z) \sim(\mathrm{Mn} z \supset \mathrm{E} z \mathrm{r}) \supset(x) \mathrm{L} x x \) } & \text {\(/ \mathrm{Laa}\) } & \text {Premise/Conclusion } \\ \text { (3) \( \sim( \) Mnn \( -\sim \) Enr \( ) \) } && \text { \( 1 \mathrm{DN} \) } \\ \text { (4) \( \sim \) (Mnn \( \supset \) Enr) } &\\\end{array}$

A) 3 DN
B) 3 DM
C) 3 Imp
D) 1 Imp
E) None of these answers are correct.