The reduced row echelon form of a system of linear equations in $x$ and $y$ or in $x$, $y$ and $z$ is given. For each system, determine whether it has a unique solution (in this case, find the solution), infinitely many solutions, or no solutions.

1. $$\left[ \begin{array}{ccc} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 0 \end{array}\right| \left. \begin{array}{c} -3 \\3\\ 4 \end{array} \right]$$
A. No solutions
B. Infinitely many solutions
C. Unique solution: $x=-3, y=3$
D. Unique solution: $x=-3, y=3, z=4$
E. Unique solution: $x=-3, y=3, z =0$
F. None of the above

2. $$\left[ \begin{array}{ccc} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 0 \end{array}\right| \left. \begin{array}{c} -3\\ 2 \\0 \end{array} \right]$$
A. Unique solution: $x=2, y=-3$
B. Infinitely many solutions
C. No solutions
D. Unique solution: $x=0, y=0, z=0$
E. Unique solution:$x=-3, y=2$
F. None of the above

3. $$\left[ \begin{array}{ccc} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array} \right| \left. \begin{array}{c} 0 \\ -3\\1 \end{array} \right]$$
A. Unique solution: $x=0, y=-3, z=1$
B. Infinitely many solutions
C. Unique solution: $x=-3, y=1$
D. Unique solution: $x=0, y=-3$
E. No solutions
F. None of the above

4. $$\left[ \begin{array}{cc} 1 & 0 \\ 0 & 1 \\ 0 & 0 \end{array} \right| \left. \begin{array}{c} 0 \\ 0 \\ 0 \end{array} \right]$$
A. Unique solution: $x=0, y=0, z = 0$
B. No solutions
C. Unique solution: $x=1, y=1 ,z = 0$
D. Infinitely many solutions
E. Unique solution: $x=0, y=0$
F. None of the above