Question

The _____ is an appropriate unit to measure the distance between two cites

Answer 1

The metric system is not a unit, so that's already ruled out. A millimeter is much much smaller than an inch and a centimeter is just a little bit bigger than an mm. So, that leaves us with options C and D. A meter is also way too small for measuring the size between two cities. So, your answer is D, kilometer.

Answer 2

Kilometers is the longest making it D.