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

Question

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

Quizplus · Accepted Answer

Line 3 is an assumption, which is a common step in proofs to derive further conclusions.

In the Following Proof, Which Justification Is Correct for Line