Question: Who assumed vocal duties on the twelfth studio album by Black Sabbath?

Context paragraphs:
The Broadways: The Broadways were a short-lived American punk band from Chicago, Illinois, formed in 1996 after the dissolution of the influential ska-punk band Slapstick.  The latter's vocalist Brendan Kelly and trumpet player Dan Hanaway assumed the roles of bassist and guitarist, joined by Rob DePaola on drums and Chris McCaughan (formerly of Tricky Dick) on guitar.  All but DePaola also assumed vocal duties.

The Best of Black Sabbath: The Best of Black Sabbath is a double CD compilation album by Black Sabbath released in 2000 on the Sanctuary Records label.  Its 32 songs are presented chronologically from the band's first 11 albums, spanning the years 1970 to 1983.  Black Sabbath's classic six-album run, from 1970s debut "Black Sabbath" through 1975's "Sabotage" is celebrated with three to six songs from each album.  Original vocalist Ozzy Osbourne's subsequent final two albums with the band, 1976's "Technical Ecstasy" and 1978's "Never Say Die! ", are represented by one and two songs, respectively.  Replacement Ronnie James Dio's early 80's stint fronting the band on two albums is acknowledged with the title track of 1980's "Heaven and Hell" and a track from 1981's "The Mob Rules".  The compilation closes with a song from 1983's attempted rebirth, "Born Again", former Deep Purple vocalist Ian Gillan's sole album with the band.  "The Best of Black Sabbath" does not include any later material with vocalists Glenn Hughes (1986's "Seventh Star"), Tony Martin (1986–96) or the returning Dio (1992's "Dehumanizer").

Heaven &amp; Hell Tour: The Heaven & Hell Tour was the ninth world concert tour by Black Sabbath between April 1980 and February 1981 to promote their 1980 studio album, "Heaven and Hell."  The tour marked the band's first live shows with vocalist Ronnie James Dio, who replaced original vocalist Ozzy Osbourne the previous year; drummer Vinny Appice, who replaced original drummer Bill Ward in the middle of the tour's North American leg after Ward suddenly left the band due to personal issues; and keyboardist Geoff Nicholls, who played keyboards on the "Heaven and Hell" album and accompanied the band on this tour as a sideman.  For a portion of the North American tour, which was popularly known as the "Black and Blue Tour", Black Sabbath co-headlined with Blue Öyster Cult, with whom they shared a manager, Sandy Pearlman.  The arrangement reportedly set attendance records but caused friction between the two bands as well as between Black Sabbath and Pearlman.

The Eternal Idol: The Eternal Idol is the thirteenth studio album by English rock band Black Sabbath, released on November 23, 1987.  It is the first Black Sabbath album to feature vocalist Tony Martin.  It spent six weeks on the "Billboard" 200 chart, peaking at 168.  It was also the last full album of new material by Black Sabbath to be released by Warner Bros.  Records (in North America), and the final album through their original label Vertigo Records until the release of "13" in 2013.

The Collection (Black Sabbath album): The Collection is a compilation album released by English heavy metal band Black Sabbath in 1992.  The album was released on the label Castle, who released two CD versions of this album in the UK, both with the same cover art and songs.  The album includes greatest songs of Black Sabbath with Ozzy Osbourne prior to his dismissal in 1979, from the eponymous album to "Never Say Die! ".  The album has 15 tracks, two from "Black Sabbath", two from "Paranoid", one from "Master of Reality", two from "Black Sabbath Vol.  4", two from "Sabbath Bloody Sabbath", two from "Sabotage", two from "Technical Ecstasy" and two from "Never Say Die! ".

Vol. 4 (Black Sabbath album): Vol.  4 is the fourth studio album by English rock band Black Sabbath, released in September 1972.  It was the first album by Black Sabbath not produced by Rodger Bain; guitarist Tony Iommi assumed production duties.  Patrick Meehan, the band's then-manager, was listed as co-producer, though his actual involvement in the album's production was minimal at best.

Seventh Star: Seventh Star is the twelfth studio album by English rock band Black Sabbath, released in January 1986.  The release came at a difficult time as the group had just finished a highly contentious tour, experiencing conflicts within the band.  With guitarist and songwriter Tony Iommi being the sole original member left, musicians Geoff Nicholls, Eric Singer, and Dave Spitz contributed to the album, playing keyboards, drums, and bass, respectively.  Glenn Hughes, ex-Deep Purple bassist and vocalist, was

Fused (album): Fused is a solo album by Black Sabbath guitarist Tony Iommi, released in 2005.  The album also features vocalist/bassist Glenn Hughes (who briefly fronted Black Sabbath in the mid-80s, assuming vocal duties on the album "Seventh Star" - an album that was originally intended to be Iommi's first solo album) and drummer Kenny Aronoff.

Streets: A Rock Opera: Streets: A Rock Opera (often simply shortened to Streets) is a concept album by Savatage, dealing with the rise and fall of the musician DT Jesus.  It was originally released in October 1991 on Atlantic Records.  The album took almost a year to record, with pre-production beginning in October 1990.  It was also Jon Oliva's last album as lead vocalist until 1995's Dead Winter Dead and 1997's The Wake of Magellan, where he shared lead vocal duties with Zak Stevens (singing lead on two songs from each album).  He resumed lead vocal duties exclusively on 2001's Poets and Madmen.

Godspeed (band): Godspeed is an American metal band formed in 1992.  Following the release of their debut album Ride on Atlantic Records, produced by Rachel Bolan of Skid Row, the band embarked on two high-profile tours as the opening act for Black Sabbath and Dio.  Godspeed gained attention with an appearance on the 1994 Black Sabbath tribute album "Nativity in Black", on which they teamed up with guest vocalist Bruce Dickinson of Iron Maiden to record a cover of the Black Sabbath song, "Sabbath Bloody Sabbath."

Supporting paragraphs: Fused (album) Seventh Star
Answer: Glenn Hughes