Which of the following technologies derives its name from a 10th century viking king?
Harald “Bluetooth” Gormsson (Old Norse: Haraldr Gormsson, Danish: Harald Blåtand Gormsen, c. 935–985/6) was a king of Denmark and Norway. He was the son of King Gorm the Old and of Thyra Dannebod. His father had been the first ruler of the Danish kingdom and founder of the Jelling Dynasty.
Harald ruled as King of Denmark from c. 958. Harald introduced Christianity to Denmark and consolidated his rule over most of Jutland and Zealand. Harald’s rule as King of Norway following the assassination of King Harald Greycloak of Norway was more tenuous, most likely lasting for no more than a few years in the 970s. Some sources say his son Sweyn Forkbeard forcibly deposed him from his Danish throne before his death.