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

full_context: Document 1: Battle of Niså: The Battle of Niså ("Slaget ved Niså") was a naval battle fought on 9 August 1062 between the forces of Norwegian king Harald Hardrada and king Sweyn II of Denmark. Harald had claimed the Danish throne since 1047, and had launched raids into Denmark ever since. With his invasion in 1062, he wanted to decisively defeat the Danes, and thus finally be able to conquer Denmark. The battle was won clearly by the Norwegians, but since many Danes managed to escape, including Sweyn, it proved indecisive in Harald's attempt to conquer Denmark.
Document 2: Battle of Stångebro: The Battle of Stångebro, or the Battle of Linköping, took place at Linköping, Sweden, on 25 September 1598 (O.S.) and effectively ended the personal union between Sweden and the Polish–Lithuanian Commonwealth, that had existed since 1592. In the battle, an army of c. 8 ,000–12,000 commanded by Duke Charles defeated a mixed force of c. 5,000–8,000 consisting of an invading army of mercenaries in the king's employ and diverse but poorly co-ordinated supporting Swedish noblemen's forces commanded by King of both Sweden and the Polish–Lithuanian Commonwealth Sigismund III Vasa, who was acting to maintain and restore his personal union against anti-Catholic forces in Lutheran Sweden. The Swedish kings general Constantin fought at the western bridge.
Document 3: Battle of Bornholm (1456): The Battle of Bornholm was a naval battle which took place near the Danish island of Bornholm, between privateers from the city of Gdańsk (Danzig) and a transport convoy of Danish and Livonian ships which were attempting to bring supplies and reinforcements to the Teutonic Knights in Prussia, during the Thirteen Years' War (1454–66) between the Kingdom of Poland and the Prussian Confederation on one hand, and the Monastic State of the Teutonic Knights on the other. The battle took place on the night of 14 August 1457.
Document 4: Öland Bridge: The Öland Bridge (Swedish: "Ölandsbron" ) is a road bridge connecting Kalmar on mainland Sweden to Färjestaden on the island of Öland to its east. At 6072 m long, it is one of the longest in all of Europe (the longest one until completion of Vasco da Gama Bridge in 1998). It is supported by 156 pillars, and has a characteristic hump at its western end which was created to provide a vertical clearance of 36 m for shipping.
Document 5: Øresund: 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.
Document 6: Battle of Vågen: The Battle of Vågen (also Battle in the Bay of Bergen, or shortened Battle of Bergen) was a naval battle between a Dutch merchant and treasure fleet and an English flotilla of warships in August 1665 as part of the Second Anglo-Dutch War. The battle took place in Vågen (meaning "the bay, voe" in Norwegian), the main port area of neutral Bergen, Norway. Due to a delay in orders the Norwegian commanders took the side of the Dutch, contrary to the secret intentions of the King of Norway and Denmark. The battle ended with the defeat of the English fleet, which retreated, much damaged but without losing any ships. The treasure fleet was relieved by the Dutch home fleet seventeen days later.
Document 7: Helsingborg: Helsingborg (] ; spelled Hälsingborg between 1912 and 1970) is a town and the seat of Helsingborg Municipality, Scania, Sweden. It had 132,989 inhabitants in 2013. Helsingborg is the centre of the northern part of western Scania. There is no formal metropolitan area, but the municipality of Helsingborg City and its neighbouring five municipalities (within Scania) had in spring of 2013 a population of 269.489 inhabitants at an area of 1.353 km2 , a population density of 200 people/km. This makes Helsingborg the fourth largest population area in Sweden. The city is also Sweden's closest point to Denmark, with the Danish city Helsingør clearly visible on the other side of the Øresund about 4 km to the west, closer than to the city's own remoter areas. If including all population around the northern part of Øresund, as a Helsingborg-Helsingør metropolitan area, its population increases to 732.450 at an area of 2.802 km2 . The busy ferry route, known as the HH Ferry route has through history been operated by several shipping lines. s of 2014 more than 70 car ferries departures from each harbour every day.
Document 8: Battle of Lund: The Battle of Lund, part of the Scanian War, was fought on December 4, 1676, in an area north of the city of Lund in Scania in southern Sweden, between the invading Danish army and the army of Charles XI of Sweden. The Danish had an army of about 13,000 under the personal command of 31-year-old King Christian V of Denmark, aided by General Carl von Arensdorff. The Swedish army, which numbered about 8,000, was commanded by Field Marshal Simon Grundel-Helmfelt and the 21-year-old Swedish king Charles XI. It is one of the bloodiest battles in percent of casualties on both sides ever fought on European soil.
Document 9: Middelgrundsfortet: Middelgrundsfortet or Fort Middelgrund is a sea fort located on an artificial island in the Øresund between Copenhagen and Malmö. The fortress is constructed at a point where the seabed is 7 meters below the water surface, and at the northern meeting point of the straits Kongedybet and Hollænderdybet.
Document 10: Battle of Nyborg: The Battle of Nyborg was a battle fought between Sweden and the combined forces of Denmark, Dutch naval forces under Michiel de Ruyter, troops of Brandenburg-Prussia, and Polish–Lithuanian Commonwealth forces under Stefan Czarniecki. The battle was engaged on 14 November 1659 at Nyborg on the Danish island of Funen. Nyborg was the final major conflict of the Dano-Swedish War of 1658 to 1660.
Document 11: Limfjord: The Limfjord (common Danish: "Limfjorden" ] , in north Jutlandish dialect: "Æ Limfjord") is a shallow part of the sea, located in Denmark where it is regarded as a fjord ever since the Vikings. However it has inlets both from the North Sea and Kattegat and hence separates the island of North Jutlandic Island (Danish: "Nørrejyske Ø", which includes the old provinces "Vendsyssel", "Han herred" and "Thy") from the rest of the Jutland Peninsula. It extends from Thyborøn Channel on the North Sea to Hals on the Kattegat. It is approximately 180 kilometres long and of an irregular shape with numerous bays, narrowings, and islands, most notably Mors, and the smaller ones Fur, Venø, Jegindø, Egholm and Livø. It is deepest at Hvalpsund (24 metres). The Limfjord is not a fjord in the English geological sense — in Danish, as in Norwegian, the term "fjord" can refer to a wide range of waterways.
Document 12: Karmsund: Karmsund is a strait located in Rogaland county, Norway. The 30 km long strait divides the island of Karmøy on the west and the mainland of Norway and island of Vestre Bokn in the east. The strait runs through the municipalities of Haugesund, Karmøy, and Bokn. The town of Haugesund lies at the northern end of the strait and the town of Kopervik lies in the central part of the strait, and the village of Skudeneshavn lies near the southern end where the strait flows into the Boknafjorden. The Karmsund Bridge, a part of the European route E134 highway, links Karmøy to the mainland. The bridge was completed in 1955. The small islands of Vibrandsøy, Risøy, and Hasseløy lie in the strait at the northern end, just off shore from the town of Haugesund.
Document 13: SL ferries: SL ferries (short for Swedish "Skandinavisk Linjetrafik" or Scandinavian Line Traffic) was a shipping line that operated with car ferries in the central part of Øresund, between Copenhagen, Port of Tuborg, Zealand, Denmark and Landskrona, Scania, Sweden. The shipping line was to sail this route between 1951 and 1980 During the first ten years of operation, the SL ferries was a Danish owned shipping line, but in 1961 SL was bought by "Stockholms Rederi AB Svea". The new owners also owned the LB (car ferries) which since 1955 operated at the HH Ferry route between Helsingør (45 km north of Copenhagen) and Helsingborg (25 km north of Landskrona), the first challenger of the "de facto" monopoly at that route which DSB had enjoyed since 1882.
Document 14: Battle of the Sound: 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.
Document 15: Akselsundet: Akselsundet is a sound between Van Mijenfjorden and Bellsund at Spitsbergen, Svalbard. It has a width of about 1.2 kilometers, located north of Akseløya, and is the main entrance to Van Mijenfjorden. There are strong tidal currents in the strait, up to five to six knots. The entrance is marked by a light at Birkelandodden, the northern point of Akseløya.
ground_truth: 4 km