Transcript text: Solve the system of linear equations using matrices.
\[
\left\{\begin{array}{rrr}
x+y & = & 1 \\
6 y & = & 12 \\
7 x+3 y-2 z & = & 5
\end{array}\right.
\]
Select the correct choice below and, if necessary, fill in the answer boxes to complete your choice.
A. The solution is ( $\square$ . $\square$ $\square$ ). (Type an exact answer in simplified form.)
B. There are infinitely many solutions.
C. There is no solution.