For this case we propose a rule of three:
1km --------------->
miles
5km ---------------> x
Where the variable "x" represents the amount of miles equivalent to 5 kilometers.
![x = \frac {5 * \frac {5} {8}} {1}\\x = \frac {25} {8}\\x = 3.125](https://img.qammunity.org/2020/formulas/mathematics/middle-school/neyro1uz93o0patclpmunotbhbgi99g5xt.png)
Thus, the race has approximately 3,125 miles, which we can round to 3 miles.
ANswer:
Option B