Question: Which singer is American, Mark King or Nick Hexum?

Context articles: Two Hearts Collide
Zack Hexum
Nick Hexum
Mark King (musician)
Amber (song)
Decomposer (album)
All Mixed Up (311 song)
I'll Be Here Awhile
Freak Out (311 song)
Freak the Freak Out

"Two Hearts Collide" is a pop/romantic song released in 1988, in the studio album "Staring at the Sun", by the British musical group Level 42.
 It was written by Mark King and Boon Gould, that had already abandoned the band.
 It was not well received by critics in the beginning, as almost all of the music of the album "Staring at the Sun", in spite of this, was well received by the fans of the band.
 This song is in the compilation released in 1998 "Turn It On".
 The lead vocals are by Mark King.
Zack Hexum (born April 28, 1978) is a Los Angeles based singer-songwriter.
 He is the younger brother of Nick Hexum, the vocalist for 311.
Nicholas Lofton "Nick" Hexum (born April 12, 1970) is an American singer, songwriter and rapper, currently the vocalist and guitarist for the multi-platinum alternative rock band 311 and The Nick Hexum Quintet.
Mark King (born 20 October 1958) is an English musician.
 He is most famous for being the lead singer and bassist of the band Level 42.
 King is known for his slap style of playing the bass guitar, with MusicRadar describing him as "the guy who put the slap in pop during the 80s".
 He won the "Outer Limits" award at the 2017 Progressive Music Awards.
"Amber" is the third single from the band 311's 2001 album "From Chaos".
 Focusing more on their reggae roots, the song is about Nick Hexum's then fiancee and then Eden's Crush member Nicole Scherzinger.
 Scherzinger appears briefly in the music video, playing in the ocean with Hexum.
 Although it is not one of the highest charting singles (hitting number 13 on the Modern Rock chart), it ended up their longest lasting on the Alternative Rock chart and remains their most popular single to date.It is also their only single that received a certification by the RIAA, achieving Gold status.
 It is considered to be the band's signature song along with "Down".
Decomposer is the second album by The Matches, released by Epitaph Records on September 11, 2006 worldwide and on September 12, 2006.
 The band took an unusual approach to the album and enlisted the help of nine producers including John Feldmann of Goldfinger, Mark Hoppus of +44 and Blink-182, Nick Hexum of 311, Tim Armstrong of Rancid and Brett Gurewitz of Bad Religion.
"All Mixed Up" is a single released by 311.
 It was on the album "311", also known as "The Blue Album".
 This album was released in 1995 and later went triple platinum, selling over 3 million copies worldwide.
 The song was co-written by Douglas Vincent "SA" Martinez and Nick Hexum.
 The duo first started working on the song during the 311 tour supporting "Grassroots".
 After the tour Martinez wrote the lyrics about feeling "confused and being unfaithful" and Hexum took the song's title from an early Elvis Presley interview in which Elvis claimed he was "all mixed up" over his new-found fame.
"I'll Be Here Awhile" is a single by alternative rock band 311.
 It is the 12th and closing track on their album "From Chaos".
 Lead singer Nick Hexum originally wrote it when he was twenty, hence the line in the refrain "Twenty years of age, " though Hexum was thirty when he recorded it.
 He comments on the interview included on the disc of "From Chaos" that he was living a wild and crazy life at that young age.
"Freak Out" is a single released by 311.
 It was on the album "Music".
 This studio single was released in 1992, prior to the release of "Music".
 All three songs appearing on this single have co-written lyrics by Douglas Vincent "SA" Martinez and Nick Hexum.
 The music for "Freak Out" was co-written by Chad Sexton and Nick Hexum.
"Freak the Freak Out" is a song performed by American pop recording artist Victoria Justice.
 It was produced by The Super Chris and Michael Corcoran, who also co-wrote the song with C.J. Abraham, Nick Hexum, Zack Hexum, Dan Schneider, for "" (2011), the soundtrack to the Nickelodeon television series, "Victorious".
 It was released as the album's lead single on November 19, 2010 through Columbia Records.
 Musically, the song is a fast-paced electronic rock song with influences of electropop and teen pop lyrics, and the lyrics speak of getting the attention of a distant boyfriend.