John starts his run by moving south, then westward, and finally he goes back north. Interestingly, the distance he runs south and then north is equal. This means that north-south run doesn't affect his distance from the initial point. The direction he is displaced from his starting point is westward due to his run in that direction.
Initially, he runs 5 miles south, then 25 miles west, and finally, he returns 5 miles north. Given that his southward and northward run distances are the same, they cancel each other out when considering John's displacement from his original position. It's as if he just ran westwards from his initial position.
Hence, the distance between his initial position and his final position will be equal to the westward run. And since he ran 25 miles west, he's 25 miles away from the initial position.
So, the answer is B) 25 miles.