B ) 1/2 mile
1) As we can see in that map, the distance between the Ranger's Cabin is the difference between 5/8 -1/8 So we can write it out:
D Ranger's Cabin =

2) Simplifying that fraction by 4 on the numerator and on the denominator, we can write that :

3) Hence, the answer is B ) 1/2 mile