Ans: D
The solution of $0\le x \le 6$ is the region on the left hand side of the line $BD$.
The solution of $0\le x \le 6$ is the region on the left hand side of the line $BD$.
The solution of $0\le y \le 3$ is the region below the line $FD$.
The solution of $x\le y$ is the region above the line $OD$.
Therefore, the overall solution of the given system of inequalities is $\Delta ODF$.
