There are a lot of forms of technology that have changed pop music! One of the biggest things is the creation of auto-tuning, which automatically corrects an artist's pitch when they are singing out of tune in the studio so that they sound perfect. They can also use this feature during concerts. Another way technology has changed pop music is in the form of launch pads. Launch pads are a board of keys that have samples placed into them by computer and a DJ can use those samples and mix music live. In the past, pop music was changed by the addition of electric guitars and keyboards! Along with those came amplifiers!
C) The composer may wish to use certain instruments to support other instruments; as the bass and harmony support the melody.