Which one of the following conditions must $p, q,$ and $r$ satisfy so that the following system of linear simultaneous equations has at least one solution, such that $p+ q + r \neq 0?$
- $x+2y-3z=p$
- $2x+6y-11z=q$
- $x-2y+7z=r$
- $5p - 2q - r=0$
- $5p + 2q + r=0$
- $5p + 2q - r=0$
- $5p - 2q + r=0$