Final answer:
Bobby's cat can run x miles in one hour at a speed of x mph, making the correct answer Option A, x miles.
Step-by-step explanation:
The question asks how far can Bobby's cat run for an hour if the cat runs at a speed of x mph. Since the speed of the cat is given as x miles per hour, this means the cat can cover x miles in one hour. The distance covered in one hour is simply the speed of the cat since speed is defined as distance divided by time. Therefore, the correct answer is Option A, x miles.