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) \( \sim \mathrm{Da} \) } &&\text { Premise} \\ \text { (2) \( (x) (\sim \mathrm{C} x \supset \mathrm{D} x) \) } & \text { \(/ \mathrm{Ca}\) }& \text { Premise/Conclusion } \\ \text { (3) \( \sim \mathrm{Cb} \supset \mathrm{Db} \) } &\\\end{array}$

A) 1 Add
B) 2 UI
C) Assumption
D) 1, 2 MT
E) None of these answers are correct.