Answer: The bottom left option.
Explanation:
←XY→ is the line that connects the points X and Y.
The fact that the planes C and D intersect at this linea, means that all the points where the planes are intersecting are points in the given line.
Then the correct option is the bottom left one, because the planes D and C are intersecting in a line, and the line passes through the points X and Y, so that line is called ←XY→.