In a step function (like what's seen), we find what f(x) is at the filled or closed circles. For f(-3), we follow the x- axis to -3 then drop down to the CLOSED circle. The open circle may come first going down the y- axis, but the open circle is not what we want.
The closed circle appears to be at -4, 4 units down from the origin.
Thus f(-3) = -4 and the first choice is best.
