If you plug in some values for x, you can graph it on the plane.
When x = 0.
[tex]\sqrt{0} = 0[/tex]
When x = 1
[tex]\sqrt{1} = 1[/tex]
When x = 4
[tex]\sqrt{4} = 2[/tex]
[tex]\sqrt{9} = 3[/tex]
Now plot the points and draw a graph through the points.
So, the last option is the answer.