Choose the figure which is different from the rest based on its boundary properties:

- AA triangle
- BA rectangle
- CA circle
- DAn open parabola (U-shaped curved line)
Solution & Step-by-step Explanation
A triangle, a rectangle, and a circle are all closed geometric figures that enclose a specific area. An open parabola (U-shaped curved line) is an open geometric figure. Thus, option D is different from the rest.