Q. Design of both summit and valley curves is based on the assumption that the

(A) curve is so flat that the length of curve is equal to the length of chord

(B) two portions of the curve along the two tangents on either side of the point of intersection are equal

(C) angles made by the tangent with the horizontal are very small and tangents of those angles are equal to the angles themselves (in radians)

(D) all of the above