Question: What instrument was the musician behind the album "In San Francisco" a famous exponent of?

full_context: Document 1: In San Francisco: In San Francisco is a live album by Hindustani classical musician Ravi Shankar. It was released in 1967 on vinyl. It was later digitally remastered and released in CD format through Angel Records.
Document 2: Shrikrishna Narayan Ratanjankar: Shrikrishna Narayan Ratanjankar (December 31, 1900 – February 14, 1974) or S N Ratanjankar was a distinguished scholar and teacher of Hindustani classical music, from the Agra gharana. Foremost disciple of Vishnu Narayan Bhatkhande and Faiyaz Khan of Baroda State, he also remained principal of Bhatkhande Music Institute ("Bhatkande Sangeet Sansthan"), Lucknow, for many years, where he trained many noted names in the field of music.
Document 3: Allauddin Khan: Allauddin Khan, also known as Baba Allauddin Khan (c. 1862 – 6 September 1972) was a sarod player and multi-instrumentalist, composer and one of the most renowned music teachers of the 20th century in Indian classical music.
Document 4: Ravi Shankar: Ravi Shankar, KBE (] ; 7 April 192011 December 2012), born Rabindra Shankar Chowdhury, his name often preceded by the title Pandit ('Master'), was a Bengali Indian musician and a composer of Hindustani classical music. He was one of the best-known exponents of the sitar in the second half of the 20th century and influenced many other musicians throughout the world.
Document 5: Ravi Shankar's Festival from India: Ravi Shankar's Festival from India is a double album by Indian musician and composer Ravi Shankar, released on World Pacific Records in December 1968. It contains studio recordings made by a large ensemble of performers, many of whom Shankar had brought to the United States from India. Among the musicians were Shivkumar Sharma, Jitendra Abhisheki, Palghat Raghu, Lakshmi Shankar, Aashish Khan and Alla Rakha. The project presented Indian classical music in an orchestral setting, so recalling Shankar's work as musical director of All India Radio in the years before he achieved international fame as a soloist during the 1960s.
Document 6: Sitar in jazz: The history of the sitar in jazz, that is the fusion of the sounds of Indian classical music with Western jazz, dates back from the late-1950s or early-1960s when musicians trained in Indian classical music such as Ravi Shankar started collaborating with jazz musicians such as Tony Scott and Bud Shank. Later jazz recordings containing sitar music include albums by Miles Davis, Alice Coltrane, Yusef Lateef, Joe Harriott (in collaboration with composer John Mayer), and Ornette Coleman.
Document 7: Improvisations (Ravi Shankar album): Improvisations is a 1962 LP album by Ravi Shankar. The opening piece is based on music from Shankar's score for Satyajit Ray's 1955 movie "Pather Panchali" with flutist Bud Shank playing in Indian style. Shankar composed "Fire Night" influenced by the 1961 Los Angeles fires and the song features jazz musicians Shank (flute) and Gary Peacock (bass) improvise over Indian percussion instruments. The concluding ragas are in classical Indian style: the first raga, Kirvani, with South Indian origin, and the second, Rageshri, with North Indian origin. The album was released in CD format by Angel Records in 1999 and has been described as a "visionary recording" by AllMusic reviewer Heather Phares.
Document 8: Ravi Shankar: In Celebration: Ravi Shankar: In Celebration is a compilation box set by Indian classical musician and composer Ravi Shankar, released in 1996 on Angel Records in conjunction with Dark Horse Records. The four discs cover Shankar's international career, from the 1950s to the mid 1990s, and include recordings originally released on the World Pacific, HMV, Angel, Apple, Dark Horse and Private Music record labels. Shankar's friend George Harrison compiled and co-produced the set, which was issued as part of year-long celebrations for Shankar's 75th birthday.
Document 9: Nikhil Banerjee: Nikhil Ranjan Banerjee (Bengali: নিখিল রঞ্জন ব্যানার্জী ) (14 October 1931 – 27 January 1986) was an Indian classical sitarist of the Maihar Gharana. A student of the legendary Baba Allauddin Khan, Pandit Nikhil Banerjee was known for his technical virtuosity and clinical execution. Along with Pandit Ravi Shankar and Ustad Vilayat Khan, he emerged as one of the leading exponents of the sitar. He was a recipient of the Indian civilian honour of the Padma Bhushan.
Document 10: Notes from San Francisco: Notes from San Francisco is a posthumous album by Irish musician Rory Gallagher. Released in 2011, It consists of two CDs. The first disc is a never released album that Gallagher recorded in San Francisco in December 1977. The album was to be a major shift for Gallagher. Rather than producing it himself he worked with Elliot Mazer a successful producer who had a long track record with artists such as Bob Dylan, Janis Joplin, and The Band. At the last minute -- causing great distress to his manager and brother Donal and to his record company -- Gallagher decided to just pull the record. In an interview Gallagher stated "it wasn't because of the material or the musicians or anything like that. It was a song thing that I didn't think on the technical side everything worked. So I scrapped the thing" After scrapping the album Gallagher reworked his band firing all the musicians except the bass player and hiring a new drummer. This new Gallagher power trio re-recorded the San Francisco songs with Gallagher producing and released them as Photo-Finish. Shortly before his death, Rory reportedly gave Donal permission to eventually release the original San Francisco versions of the songs if they were remixed. Donal had his son Daniel remix the songs in 2011. The second disc is a live performance also recorded in San Francisco in December 1979.
Document 11: Ravi Shankar's Music Festival from India: Ravi Shankar's Music Festival from India was an Indian classical music revue led by sitarist and composer Ravi Shankar intended for Western concert audiences and performed in 1974. Its presentation was the first project undertaken by the Material World Charitable Foundation, set up the previous year by ex-Beatle George Harrison. Long a champion of Indian music, Harrison also produced an eponymous studio album by the Music Festival orchestra, which was released in 1976 on his Dark Horse record label. Both the CD format of the Ravi Shankar's Music Festival from India album and a DVD of their performance at the Royal Albert Hall in London were issued for the first time on the 2010 Shankar–Harrison box set "Collaborations".
Document 12: Rabin Ghosh: Rabin Ghosh (1932–2010), a 20th-century violin virtuoso of 'Seni-Maihar' Gharana (Seni-Maihar School of thoughts) of North Indian Classical Music, India, was a disciple of Baba Ustad Allauddin Khan Saheb.
Document 13: Vilayat Khan: Ustad Vilayat Khan (28 August 1928 – 13 March 2004) was one of India's well known sitar maestros. Along with Ravi Shankar, Ali Akbar Khan, Nikhil Banerjee and his younger brother Imrat Khan, Vilayat Khan helped introduce Indian Classical Music to the West.
Document 14: Ram Narayan: Ram Narayan (Hindi: राम नारायण ; IAST: Rām Nārāyaṇ , ] ; born 25 December 1927), often referred to with the title Pandit, is an Indian musician who popularised the bowed instrument sarangi as a solo concert instrument in Hindustani classical music and became the first internationally successful sarangi player.
Document 15: Music in Varanasi: Music in Varanasi is a tradition linked to the ancient times of the Pauranic legends. Lord Shiva, who is reported to have established this city, was credited with developing music and dance forms. Legend also attributes that Renu, son of sage Vishvamitra and Mahagobind, was the precursors of music tradition in Kashi (Varanasi) when nymphs (Apsaras), Gandharvas and Kinnaras were the traditional practitioners of this art form, and saint Chaitanya and Vallabhacharya were the pioneers in spreading this music tradition in Varanasi. Notable musicians of Varanasi include the iconic sitar player Ravi Shankar, the Shehnai maestro Bismillah Khan, and the vocal music singer Girija Devi. Varanasi has joined the global bandwagon of UNESCO "Cities of Music" under the Creative Cities Network. Varanasi chosen in music category of creative cities network clearly signifies the rich musical heritage of this ancient city.
ground_truth: sitar