Answer: C) 0
This is the x intercept because y = 0 here. The full location is (x,y) = (4,0)
Effectively, you draw a vertical line through x = 4 to see where it crosses the function curve. Call this point P. Then from point P, you draw a horizontal line to the y axis to see what the y coordinate of that point is. In this case, P = (4,0).
