Q:Information:  - 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.  - 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.  - 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 .  - 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.  - 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 Buffett, 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.    After reading the paragraphs above, we are interested in knowing the entity with which 'michael sweet' exhibits the relationship of 'instrument'. Find the answer from the choices below.  Choices: - bass  - bass guitar  - guitar
A:
bass guitar