Hard rock
Established acts benefited from the new commercial climate, with Whitesnake's self-titled album (1987) selling over 17 million copies, outperforming anything in Coverdale's or Deep Purple's catalogue before or since. It featured the rock anthem "Here I Go Again '87" as one of 4 UK top 20 singles. The follow-up Slip of the Tongue (1989) went platinum, but according to critics Steve Erlwine and Greg Prato, "it was a considerable disappointment after the across-the-board success of Whitesnake". Aerosmith's comeback album Permanent Vacation (1987) would begin a decade long revival of their popularity. Crazy Nights (1987) by Kiss was the band's highest charting release in the US since 1979 and the highest of their career in the UK. Mötley Crüe with Girls, Girls, Girls (1987) continued their commercial success and Def Leppard with Hysteria (1987) hit their commercial peak, the latter producing seven hit singles (a record for a hard rock act). Guns N' Roses released the best-selling début of all time, Appetite for Destruction (1987). With a "grittier" and "rawer" sound than most glam metal, it produced three top 10 hits, including the number one "Sweet Child O' Mine". Some of the glam rock bands that formed in the mid-1980s, such as White Lion and Cinderella experienced their biggest success during this period with their respective albums Pride (1987) and Long Cold Winter (1988) both going multi-platinum and launching a series of hit singles. In the last years of the decade, the most notable successes were New Jersey (1988) by Bon Jovi, OU812 (1988) by Van Halen, Open Up and Say... Ahh! (1988) by Poison, Pump (1989) by Aerosmith, and Mötley Crüe's most commercially successful album Dr. Feelgood (1989). New Jersey spawned five Top 10 singles, a record for a hard rock act. In 1988 from 25 June to 5 November, the number one spot on the Billboard 200 album chart was held by a hard rock album for 18 out of 20 consecutive weeks; the albums were OU812, Hysteria, Appetite for Destruction, and New Jersey. A final wave of glam rock bands arrived in the late 1980s, and experienced success with multi-platinum albums and hit singles from 1989 until the early 1990s, among them Extreme, Warrant Slaughter and FireHouse. Skid Row also released their eponymous début (1989), reaching number six on the Billboard 200, but they were to be one of the last major bands that emerged in the glam rock era.

Q: Def Leppard's album Hysteria churned out how many hit singles?
seven