Final answer:
In "Smoke on the Water" by Deep Purple, the guitar and bass are playing almost the same part, with the bass often doubling the guitar riff.
Step-by-step explanation:
The relationship between the guitar and bass parts in the first verse of "Smoke on the Water" by Deep Purple can best be described as c. they are playing almost the same part. During this iconic song, the guitar lays down a distinctive riff composed of a series of fourths, which is immediately recognizable. The bass part closely follows the guitar riff, often playing the same notes an octave lower or doubling the riff. The interplay between the guitar and bass provides a strong foundation for the song, where both instruments support the rhythm together rather than the bass part moving faster or having a rhythm guitar role or sustained rhythm parts.