To find this, you have to find your slope with the given x and y values first. Use the equation Y2-Y1/X2-X1 for finding the slope.
4-1/3- -6
3/9= 1/3
Now you know your slope is 1/3, and you can basically assume your third answer listed is correct since none of the other ones contain a positive 1/3 but I will explain how to continue for future use. Next you can use one set of x and y values to plug into the equation y=mx+b, and plug in 1/3 for m as well.
4=1/3(3) + b
4 = 1 + b
-1 -1
3 = b
Now you have your y intercept and your slope, so you can make your equation.
Y= 1/3x + 3