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

Context paragraphs:
Otahuhu: Ōtāhuhu is a suburb of Auckland 13 km to the southeast of the Auckland CBD, on a narrow isthmus between an arm of the Manukau Harbour to the west and the Tamaki River estuary to the east.  The isthmus is the narrowest connection between the North Auckland Peninsula and the rest of the North Island, being only some 1200 metres wide at its narrowest point, between the Ōtāhuhu Creek and the Mangere Inlet.  As the southernmost suburb of the former Auckland City it is considered part of South Auckland.

Fan Tan Alley: Fan Tan Alley (番攤里) is an alley in Victoria, British Columbia's Chinatown.  It runs south from Fisgard Avenue to Pandora Avenue in the block between Government Street and Store Street.  Named after the Chinese gambling game Fan-Tan, the alley was originally a gambling district with restaurants, shops, and opium dens.  Today it is a tourist destination with many small shops including a barber shop, art gallery, Chinese cafe, apartments and offices.  It is the narrowest street in Canada.  At its narrowest point it is only 0.9 m wide.  It was designated as a heritage property by the local government in 2001.

Younghusband Peninsula: Younghusband Peninsula is a long narrow peninsula in South Australia.  It separates the Coorong Channel, the Tauwitchere Channel and the Coorong which are part of the estuary of the River Murray from the Southern Ocean which including water bodies such as Encounter and Lacepede Bays.  It lies entirely within the Coorong National Park.  The peninsula is over 110 km long, but less than 3 km wide at its widest point.  Its narrowest point is less than 350 m wide.  The Younghusband Peninsula, together with the Sir Richard Peninsula on the western side of the Murray Mouth, are the coastal dune system that forms the continental coastline from near Goolwa in the north west to about 35 km north of Kingston SE in the south east.  Younghusband Peninsula was named after William Younghusband, M.P.

Qianshi Hutong: Qianshi hutong () translated as "money market hutong", is a Beijing hutong recognized as the narrowest in the city.  The street is located near to Qianmen, in the Dongcheng district.  For most of its 55 m length it is 70 cm wide and measures 40 cm at its narrowest point, requiring passersby to turn sideways.

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.

Lang Sound: Lang Sound ( ) is a sound 1.5 nmi wide at its narrowest point and 9 nmi long, lying between the group of islands that includes Broka Island and Havstein Island and Law Promontory.  It was mapped by Norwegian cartographers from aerial photographs taken by the Lars Christensen Expedition in January–February 1937 and named Langsundet (the long sound).

Quadra Island: Quadra Island is an island off the eastern coast of Vancouver Island, British Columbia, Canada, part of the Discovery Islands located within the Strathcona Regional District.  Quadra Island is about 35 km from its northernmost point to its southernmost point.  The island at its narrowest point, on its southern peninsula, is less than 2 km wide, and at its widest point, about 15 km wide.  In area Quadra island comprises about 310 km2 .  The population of island and surrounding mainland inlets, as of the 2006 federal census (excluding First Nations Reserves, tallied separately), was 2,472, down from the 2001 federal census count of 2,548.  In 1903 it was named after the Spanish navigator Juan Francisco de la Bodega y Quadra, who explored and settled the Vancouver Island area in the late 18th century.  It is separated from Vancouver Island by Discovery Passage, and from Cortes Island, and is linked to that island by a ferry from Heriot Bay on its eastern shore.  The island has many beaches, trails, lakes, and parks.  Main Lake Provincial Park is located on the northern part of the island, and Rebecca Spit Marine Provincial Park is on the eastern shore, near Heriot Bay.

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.

Bauza Island: Bauza Island lies immediately south of the much larger Secretary Island in the outer Doubtful Sound, in Fiordland National Park, in New Zealand's South Island.  The less than one kilometre wide Patea passage to the south of the island is the main entrance to Doubtful Sound.  To the north, the island is separated from Secretary Island by the narrow Te Awaatu Channel, also referred to as "The Gut", only 200 m wide at its narrowest point.  The waters between the two islands are protected by the Te Awaatu Channel (The Gut) Marine Reserve.  Doubtful Sound tour boats routinely travel through this channel.

Mycale Strait: The Mycale Strait (Greek: Στενό της Μυκάλης ) is a narrow strait separating the island of Samos from Anatolia (Turkey).  At its narrowest point it is only 1.6 km wide, the narrowest between any Aegean island and Turkey.  It is named after the nearby Mount Mycale on the Turkish mainland.  The Dilek Peninsula-Büyük Menderes Delta National Park, located in the Kuşadası district of Aydın Province, is situated along the strait.

Supporting paragraphs: Battle of the Sound Øresund
Answer: 4 km