3. 甲, 乙, 丙 answer the same 7 true/false questions, and their answers are as follows:
\begin{tabular}{|c|c|c|c|c|c|c|c|}
\hline & 1 & 2 & 3 & 4 & 5 & 6 & 7 \\
\hline 甲 & X & $\checkmark$ & X & $\checkmark$ & $\checkmark$ & X & X \\
\hline 乙 & X & $\checkmark$ & $\checkmark$ & X & X & X & $\checkmark$ \\
\hline 丙 & X & X & X & X & $\checkmark$ & $\checkmark$ & $\checkmark$ \\
\hline
\end{tabular}

It turns out that they all answered 5 questions correctly and 2 questions incorrectly. 甲 answered incorrectly ( ).
A. Question 4 and Question 6
B. Question 2 and Question 3
C. Question 4 and Question 7
D. Question 3 and Question 4
E. Question 3 and Question 5
$\mathrm{C}$