Detailed Instructions: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to build a dog barrier for your vehicle [title] Measure your vehicle's interior. [step] The size of your dog barrier will depend on the floor-to-ceiling and wall-to-wall lengths of your vehicle's trunk area. If your vehicle has collapsible back seats, you have the choice of placing the barrier just behind the front seats. <sep> (A) If you have a door-to-roof barrier, you can measure this distance and make sure it is in need of repairs. [substeps] If the doors of the car are not out of place, you can measure them at your local hardware store. (B) In this case, run a tape measure from the floor just behind the front seats up to the ceiling. Otherwise, just measure the floor-to-ceiling height of the trunk area behind the back seats. (C) [substeps] Measure out several components (for small vehicles, car piers, etc. ) that may not be able to reach the car. (D) If it has collapsible front seats, place the barrier in front of the rear doors. [substeps] If you have wide aisles, you can support this barrier with your trunk/deck metal.
A:
B