Reconstruct a question, answer pair from this explanation: The relevant sentence in the passage is: The most densely populated sovereign nation is Monaco, with a population density of 18,713 people / km.
Q:Context: The European Union is a sui generis supranational union possessing "country-like" characteristics. The entity is composed of 28 member countries. Its population density has been estimated at 116 people per km, and it would be ranked 95th if it were included in the list. (population: 506,913,394 on January 1, 2014, area: 4,324,782 km). See also: List of regional organizations by population. The most densely populated sovereign nation is Monaco, with a population density of 18,713 people / km. Area includes land and water.

Question: country with highest population density per square mile?
A:Monaco