Please answer the following question: Information:  - The guitar is a musical instrument classified as a string instrument with anywhere from four to 18 strings, usually having six. The sound is projected either acoustically, using a hollow wooden or plastic and wood box (for an acoustic guitar), or through electrical amplifier and a speaker (for an electric guitar). It is typically played by strumming or plucking the strings with the fingers, thumb and/or fingernails of the right hand or with a pick while fretting (or pressing against the frets) the strings with the fingers of the left hand. The guitar is a type of chordophone, traditionally constructed from wood and strung with either gut, nylon or steel strings and distinguished from other chordophones by its construction and tuning. The modern guitar was preceded by the gittern, the vihuela, the four-course Renaissance guitar, and the five-course baroque guitar, all of which contributed to the development of the modern six-string instrument.  - Christian metal, also known as white metal or heavenly metal, is a form of heavy metal music usually defined by its message using song lyrics as well as the dedication of the band members to Christianity. Christian metal is typically performed by professed Christians sometimes principally for Christians who listen to heavy metal music and often produced and distributed through various Christian networks.  - Strange Celebrity was a Christian rock band, formed in Nashville, Tennessee, composing of four members: Luke Brown (lead vocals, guitar), Rick Wilson (drums), Quinton Gibson (guitar), and Tracy Ferrie (bass guitar). The band is now defunct, as Luke Brown has pursued a solo career.  - Timothy "Tim" Gaines (born Timothy Hagelganz; December 15, 1962) is an American bass guitarist. He is most known for being the bassist of the Christian metal band Stryper.  - Tracy Ferrie is the current touring bass player for the classic rock band Boston and was the former bass player of Christian metal band Stryper . Beginning in 1996 , Tracy played bass for Michael Sweet 's solo band and was also a member of the bands Electrik , Sally Steele , Seraiah , Whitecross , Guardian , Rebecca St. James , Plumb , Sonicflood and Strange Celebrity . He is from Elkhart , Indiana and a national roller skating champion . Tracy is a Berklee College of Music alumni and a prominent session bass player . He participated on stage in the Boston Strong Benefit along with Aerosmith , J. Geils , Jimmy Buffet , Carol King and James Taylor . As a member of Stryper , Tracy was joined By Tom Scholz and Gary Phil to play `` Peace of Mind '' for the Station nightclub fire benefit for the families and victims of the tragic fire in Rhode Island . Some of his recording credits are with Stryper , Plumb , April McLean , Strange Celebrity , Whitecross , Jeff Deyo , Boe Braswell , Kristy Starling , Danielle Bollinger , Paul Alan , and Kimberly Locke . Tracy is the Assistant Minister at Grace Church of East Dennis on Cape Cod. During mid- 2012 , Ferrie toured with Boston , replacing Kimberley Dahme .  - Whitecross is a Christian metal band that formed in 1985 in Waukegan, IL releasing their first recording in 1987. Their early albums, which often invite comparisons to Ratt, are laced with fast, technical guitar work. In 1994, Rex Carroll split with lead vocalist Scott Wenzel. Scott retained the use of the name "Whitecross" while Carroll went on to form King James with Jimi Bennett (see below). At this point the band's sound underwent a drastic change.  - Stryper is an American Christian heavy metal band from Orange County, California. The group's lineup consists of Michael Sweet (lead vocals, guitar), Oz Fox (guitar), Tim Gaines (bass guitar), and Robert Sweet (drums). In 2004, Gaines left the band and was replaced by Tracy Ferrie (bass guitar) but rejoined in 2009.  - Michael Harrison Sweet (born July 4, 1963) is a singer from Whittier, California; he is the co-founder, writer, lead guitarist, lead singer and front man of the Christian metal band Stryper. He was also singer and guitarist for Boston from 2007 to 2011.  - Heavy metal (or simply metal) is a genre of rock music that developed in the late 1960s and early 1970s, largely in the United Kingdom and the United States. With roots in blues rock and psychedelic/acid rock, the bands that created heavy metal developed a thick, massive sound, characterized by highly amplified distortion, extended guitar solos, emphatic beats, and overall loudness. Heavy metal lyrics and performance styles are sometimes associated with aggression and machismo.    What is the relationship between 'tracy ferrie' and 'bass guitar'?
Answer:
instrument