Consider the following characteristics of contour:
(A) A uniform slope is indicated when contour lines are spaced uniformly
(B) Contour lines cannot go anywhere but can close on themselves
(C) A set of closed contours indicates a depression or a summit, according to the lower or higher values being respectively inward
(D) A contour is an imaginary line passing through the points of an equal level on the surface of earth
Choose the correct answer from the options given below: