The answer if the option B. 51 kilometers. To reply this question you have to use the fact that scientific researches are compeled to use the SI units. Inches are miles do not belong to the SI units and kilograns is not a unit of distance. The base unit of distance in the SI is the meter, but this system permits the use of multiples of ten. kilo means 1000 times this is kilometer is 1000 meters and is accepted as a unit in scientific works.