Pick up the incorrect statement from the following:
(A) Highways are always constructed in straight line
(B) Highways may be provided horizontal curves
(C) Highways may be provided vertical curves
(D) Highways may be provided both horizontal and vertical curves
(A) Highways are always constructed in straight line
(B) Highways may be provided horizontal curves
(C) Highways may be provided vertical curves
(D) Highways may be provided both horizontal and vertical curves