Final answer:
The sackbut is the predecessor to the modern trombone, an instrument that modifies pitch through a slide mechanism rather than finger holes.
Step-by-step explanation:
The ancestor of the modern trombone is the sackbut. This earlier version of the trombone was used in the Renaissance and Baroque eras. Similar to modern trombones, the sackbut changes pitch by varying the length of its sliding tube, unlike other wind instruments like the flute or oboe that change pitch using finger holes, or the bugle which has a fixed length and can only produce a limited range of frequencies. The trombone, along with instruments like the tuba that produce very low frequencies, use long tubes that are often coiled into loops to accommodate their length while maintaining playability.