For the function, find the point(s) on the graph at which the tangent line is horizontal. y =x - 8x + 16x + 1 .. . Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. The point(s) at which the tangent line is horizontal is(are) (Simplify your answer. Type an ordered pair. Use a comma to separate answers as needed.) O B. The tangent line is horizontal at all points of the graph. O C. There are no points on the graph where the tangent line is horizontal