Identify the correct statements:
i. Contour lines form sharp V-shaped curves across valley line, with the convex side of the curve towards the higher ground.
ii. Contour lines from U-shaped curves across valley line, with the convex side of the curve towards the higher ground.
iii. Contour lines form U-shaped curves across ridge line, with the concave side of the curve towards the higher ground.
iv. Contour lines form sharp U-shaped curves across ridge line, with the convex side of the curve towards the higher ground.

Correct option is D

Characteristics of contour lines:
All the points of the contour line have the same elevation.
Two contour lines do not intersect each other except in the case of an overhanging cliff or a cave penetrating a hillside.
Equally spaced contour represents a uniform slope and contours that well apart represent a gentle slope.
Contour line is a closed curve, they may close either on the map or outside the map it depending on the topography.
A set of close contours with higher figures inside and lower figures outside indicates a hillock, whereas in the case of depressions lakes, etc., the lower figures are inside and higher figures are outside.
Contour lines of a V shape with convexity towards higher ground represent the valley.
Contour lines of a U shape with convexity towards the lower ground (or with concavity towards the higher ground) represent the ridge line.