For each system, determine whether it has a unique solution (in this case, find the solution), infinitely many solutions, or no solutions.

1. $\displaystyle \left\{ \begin{array}{r@{}r@{}r@{}r} 8 x & - 9 y & = & 0 \cr 8 x & +6 y & = & 0 \end{array} \right.$
   
   A. Infinitely many solutions
   B. Unique solution: $x=-1,\ y=14$
   C. Unique solution: $x=-6,\ y=8$
   D. No solutions
   E. Unique solution: $x=0,\ y=0$
   F. None of the above
   
   
   
2. $\displaystyle \left\{ \begin{array}{r@{}r@{}r@{}r} 4 x & +4 y & = & 16 \cr -4 x & - 4 y & = & -15 \end{array} \right.$
   
   A. Unique solution: $x=16,\ y=-15$
   B. No solutions
   C. Unique solution: $x=-15,\ y=16$
   D. Infinitely many solutions
   E. Unique solution: $x=0,\ y=0$
   F. None of the above
   
   
   
3. $\displaystyle \left\{ \begin{array}{r@{}r@{}r@{}r} 3 x & - 6 y & = & 57 \cr 9 x & - 7 y & = & 105 \end{array} \right.$
   
   A. Unique solution: $x=-6,\ y=7$
   B. Unique solution: $x=7,\ y=-6$
   C. No solutions
   D. Unique solution: $x=0,\ y=0$
   E. Infinitely many solutions
   F. None of the above
   
   
   
4. $\displaystyle \left\{ \begin{array}{r@{}r@{}r@{}r} -2 x & +2 y & = & 14 \cr -4 x & +4 y & = & 28 \end{array} \right.$
   
   A. Unique solution: $x=14,\ y=28$
   B. No solutions
   C. Unique solution: $x=-7,\ y=0$
   D. Infinitely many solutions
   E. Unique solution: $x=0,\ y=0$
   F. None of the above