Answer: C. I, II, and III only
Basically everything but statement IV is true
Horizontal lines always have a slope of 0 to indicate no rise is going on.
Vertical lines have undefined slopes which you can see through the slope formula (recall that you cannot divide by zero).
Line 'a' goes through the point (5,0) making statement III true. However, statement IV is false because (-5,0) is not on line b. Line b is parallel to the x axis, so it does not have an x intercept.