 So let's go through these possible answers one at a time, starting with C. So C says the problem is time dilation. Because of the high speed, Bob won't be able to close the garage door in time. But there's a problem with this. In Bob's frame of reference, she and the garage are stationary. You never notice yourself to be time dilated. From Bob's point of view, it's Alice in the car moving at speed V, who is undergoing time dilation and living in slow motion. And that won't affect Bob's ability to close the garage door. So we can discount answer C. So what about answer B? So we've said that inertial reference frames can't be accelerating. They have to be moving at a constant speed. And obviously for Alice to reach speed V, she's going to have to do some serious accelerating. However, this acceleration is not relevant to the problem. Because Alice can start off really far away and get all her acceleration done over there so that by the time she approaches the garage, she is moving at a constant speed V and so is a perfectly valid frame of reference. Because of this, we can discount answer B. So that leaves us with answer A. Bob in his reference frame sees Alice fit inside the garage while Alice sees herself as not fit in. But didn't we say in the previous section that outcomes of experiments can't be relative? Well, the thing is, there is no contradiction between Bob saying Alice will fit inside the garage and Alice seeing herself as not fitting. Because we've seen that things like length or how long something takes can all depend on what frame you're in. What's physically important is what does the same look like at the end. Regardless of if you're in Bob's frame or if you're in Alice's frame, they both agree that the outcome of the experiment is Bob's garage being smashed to pieces and Alice driving right through it.