I would plug in each of the solutions to every equation and see which one works. This is probably easier than solving for x, y, and z. But let me know if you would like me to run through the steps!
First choice: using the first equation, -3(-3)-4(4)+6=-19 not -1 as listed. False.
Second choice: using the first equation, -3(4)-4(-3)+(-1)=-1 ; using the second equation, 2(4)+(-3)-(-1)=6 not -8 as listed. False.
Third choice: using the first equation, -3(-3)-4(4)+8=-17 not -1 as listed. False.
Fourth choice: using the first equation, -3(3)-4(-4)+-(-6)=-1 ; using the second equation,
2(3)+(-4)-(-6)=8 ; using the third equation, 3+8(-4)-(-6)=23
So the answer should be the fourth choice. Hope this helps! :)