Concept:Intervisibility is possible when the intervening slope is straight/uniform, since a convex bulge would block the line of sight.Explanation:The contours between X and Y are evenly spaced, indicating a rectilinear slope.A rectilinear slope has a uniform gradient, so the line of sight from X to Y is not obstructed by any convex bulge.Therefore, intervisibility is possible.Answer:B. Rectilinear
