Final answer:
A Drum Rack is best described as a virtual instrument within digital audio workstations for playing and sequencing drum sounds.
Step-by-step explanation:
The best way to describe a Drum Rack is c) it is a virtual instrument for playing drum sounds. A Drum Rack is commonly found within digital audio workstations (DAWs) and provides users with the ability to load, sequence, and trigger drum samples using MIDI information. It allows for layering multiple sounds on a single pad, giving producers and musicians the power to create complex and unique drum beats. Unlike hardware devices or dedicated MIDI controllers, a Drum Rack is a software component that emulates the playing of a drum kit.