You will be given a definition of a task first, then some input of the task.
In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.

Passage: Bush attended St Joseph's Convent Grammar School, a Catholic girls' school in nearby Abbey Wood which, in 1975, after she had left, became part of St Mary's and St Joseph's School in Sidcup. During this time her family produced a demo tape with over 50 of her compositions, which was turned down by record labels. Pink Floyd guitarist David Gilmour received the demo from Ricky Hopper, a mutual friend of Gilmour and the Bush family. Impressed, Gilmour helped the sixteen-year-old Bush record a more professional demo tape. Three tracks in total were recorded and paid for by Gilmour. The tape was produced by Gilmour's friend Andrew Powell, who went on to produce Bush's first two albums, and sound engineer Geoff Emerick, who had worked with the Beatles. The tape was sent to EMI executive Terry Slater, who signed her.The British record industry was reaching a point of stagnation. Progressive rock was very popular and visually oriented rock performers were growing in popularity, thus record labels looking for the next big thing were considering experimental acts. Bush was put on retainer for two years by Bob Mercer, managing director of EMI group-repertoire division. According to Mercer, he felt Bush's material was good enough to release, but felt that if the album failed it would be demoralising and if it was successful Bush was too young to handle it. However, in a 1987 interview, Gilmour disputed this version of events, blaming EMI for initially using "wrong" producers.
After the contract signing, EMI gave her a large advance, which she used to enroll in interpretive dance classes taught by Lindsay Kemp, a former teacher of David Bowie, and mime training with Adam Darius. For the first two years of her contract, Bush spent more time on school work than recording. She left school after doing her mock A-levels and having gained ten GCE O-Level qualifications.Bush wrote and made demos of almost 200 songs, some of which circulated as bootlegs known as the Phoenix Recordings. From March to August 1977, she fronted the KT Bush Band at public houses in London. The band included Del Palmer (bass), Brian Bath (guitar), and Vic King (drums). She began recording her first album in August 1977, although the tracks "The Saxophone Song" and "The Man with the Child in His Eyes" had been recorded in mid-1975.
Output:
What is the name of the person that Geoff emerick worked on their demo?