In the Following Proof, Which Justification Is Correct for Line

Multiple Choice

In the following proof, which justification is correct for line 3? $\begin{array}{llcc} \text { (1) \( (x) [(\mathrm{C} x \cdot \mathrm{D} x) \equiv \sim \mathrm{E} x] \) } & & \text { Premise} \\ \text { (2) \( \mathrm{Ca} \cdot \mathrm{Ea} \) } & \text { \(/ \sim \mathrm{Da}\) } & \text { Premise/Conclusion } \\ \text { (3) \( (\mathrm{Ca} \cdot \mathrm{Da}) \equiv \sim \mathrm{Ea} \) } &\\\end{array}$

A) 1 UG
B) 1 Simp
C) Assumption
D) 3 Add
E) None of these answers are correct.