The parent function y = sqrt(x) has the point (0,0) on it. When we subtract 3, we get y = sqrt(x)-3 which moves the point (0,0) three units down to get to (0,-3)
The square root of a function could be smaller than 3, so the function could evaluate to less than 0, but the other 3 don't have any points smaller than 0. Therefore, the only possible option is the 2nd one.
Also, if you try to evaluate it in x = 0, which is sqrt(0)-3 = -3, the only option that satisfies that would be the second one.
