Question: Hollies Sing Hollies is the ninth studio album released by an English pop/roc group best known for their pioneering and distinctive what?

Context paragraphs:
Confessions of the Mind: Confessions of the Mind is the 1970 released album by The Hollies.  It was released in the United States as "Moving Finger", with a different track sequence, the tracks "Separated" and "I Wanna Shout" omitted and replaced with the Clarke/Sylvester penned "Marigold: Gloria Swansong" saved from the previous album ("Hollies Sing Hollies" aka "He Ain't Heavy, He's My Brother" - U.S.) and "Gasoline Alley Bred".  In Germany, it was released as "The Hollies Move On".  The UK version peaked at UK #30.  The US version peaked at US #183.

The Hollies: The Hollies are an English pop/rock group, best known for their pioneering and distinctive three-part vocal harmony style.  The Hollies became one of the leading British groups of the 1960s (231 weeks on the UK singles charts during the 1960s; the 9th highest of any artist of the decade) and into the mid 1970s.  It was formed by Allan Clarke and Graham Nash in 1962 as a Merseybeat type music group in Manchester, although some of the band members came from towns north of there.  Graham Nash left the group in 1968 to form the supergroup Crosby, Stills & Nash.

Butterfly (The Hollies album): Butterfly is the second studio album released by British band The Hollies in 1967, their seventh in England overall.  It was also the last new Hollies album to feature Graham Nash until 1983's "What Goes Around".  This, like its predecessors "For Certain Because" and "Evolution", featured songs written solely by Allan Clarke, Graham Nash, and Tony Hicks.

Hollies Sing Hollies: Hollies Sing Hollies is the ninth studio album released in England by The Hollies.  It was released in November 1969 by Parlophone, their second album that year coming 6 months after an entire album of Bob Dylan covers.  It was their first album of original compositions since the departure of Graham Nash and the second album by The Hollies to feature Terry Sylvester, on rhythm guitar and first to feature Terry Sylvester compositions as well as an instrumental composition by bassist Bernie Calvert.  The U.S. version, titled "He Ain't Heavy, He's My Brother", included the hit single by the same name, while omitting the tracks "Soldier's Dilemma" and "Marigold: Gloria Swansong".  The UK album did not chart, but its U.S. version peaked at #32.

Sing Hollies in Reverse: Sing Hollies in Reverse is a tribute album of various artists performing songs by British rock group The Hollies.  It was released on Eggbert Records in 1995.

...&quot;Let Me Sing&quot;: ..."Let Me Sing" is the ninth studio album by American pop and country artist Brenda Lee.  The album was released September 12, 1963, on Decca Records and was produced by Owen Bradley.  The album was the second and final album studio album released by Brenda Lee in 1963.

In The Hollies Style: In The Hollies Style is the second studio album by British beat group The Hollies, released on the Parlophone label in November 1964.  The album was later released in Canada by Capitol Records on 4 October 1965 with a different track listing.

Five Three One - Double Seven O Four: Five Three One - Double Seven O Four is the twentieth studio album by the English rock/pop group The Hollies.  When rendered as digits, the album title is the band's name upside down in digital number view (it would appear like this: hOLLIES or 5317704).

Yes I Will: "Yes I Will", also known as "I'll Be True to You", is a song written by Gerry Goffin and Russ Titelman.  The song was first recorded in 1964 by British Beat group The Hollies who released it as a single in January 1965 where it peaked at number 9 in the United Kingdom.  Two versions of this song were released by the Hollies.  An alternate take with prominent acoustic guitars and a different intro was included on the band's 1968 Greatest Hits album in the UK since the original single version was only available as a mono mix, and EMI wanted all tracks in stereo, for which only the alternate take existed.  This is often described as an "erroneous" version because it does not reflect what was heard on the single.  Other examples of this practice include Stay from 1963 in which the famous guitar solo in the middle-eight was recorded live as the mono mix was being made, meaning the stereo version has a different solo, the one that was previously recorded on the multi-(4) track studio tape.  A version of the song titled "I'll Be True to You" was recorded by The Monkees and included on their 1966 self-titled debut album.  Australia's Twilights also recorded a version on their eponymous 1966 album.

Swing Out Sister: Swing Out Sister are an English pop group best known worldwide for the 1986 song "Breakout".  Other hits include "Surrender", "Twilight World", "Waiting Game" and a remake of the Eugene Record soul composition "Am I the Same Girl?"

Supporting paragraphs: Hollies Sing Hollies The Hollies
Answer: three-part vocal harmony style