Since the inequality has a greater or equal sign, the boundary line of inequality must be a solid line.
So, options on the left side are out.
Now, it says that y ≥ 1-3x, so the shaded area must be above the y-axis.
Test a point to see if it satisfies the inequality:
x=0 and y =0 ; y ≥ 1-3x
0 ≥ 1-3(0)
0 ≥ 1
Since the point doesn't satisfy the inequality, point (0,0) doesn't belong to the shaded region.
Correct option is the top right one.