Question: How wide is the location of the Battle of the Sound at its narrowest point?

Related documents: [0]  [DOC] Øresund or Öresund (Danish: "Øresund" , ] ; Swedish: "Öresund" , ] ), commonly known in English as the Sound, is a strait which forms the Danish–Swedish border, separating Sjælland (Denmark) from Skåne (Sweden). The strait has a length of 118 km and the width varies from 4 km to 28 km . It is 4 km wide at its narrowest point between Helsingør in Denmark and Helsingborg in Sweden. [END] 
[1]  [DOC] The naval Battle of the Sound took place on 8 November 1658 (29 October O.S.) during the Second Northern War, near the Sound or Øresund, just north of the Danish capital, Copenhagen. Sweden had invaded Denmark and an army under Charles X of Sweden had Copenhagen itself under siege. The Dutch fleet was sent to prevent Sweden from gaining control of both sides of the Sound and thereby controlling access to the Baltic Sea as well as of its trade. [END]  
Answer: 4 km
4 km