A system is inconsistent when its two equations are contradictory. In this case we have:
[tex]\mleft\{\begin{aligned}2x-4y=6 \\ x-y=-3\end{aligned}\mright.[/tex]
If we replace the second equation by :
[tex]x-2y=-3[/tex]
We get an inconsistent system. Because the first equation and the second one would be contradicting itself. So the correct option is: B
