What is the name of a piece that involves the repetition of an entire theme in another voice, possibly at a different pitch?

The correct answer is the term "Canon." A canon is a musical structure where an entire theme or melody is introduced by one voice and then exactly imitated by another voice, typically at a different pitch. This technique creates harmony and rich texture as the same melodic material is woven through different musical lines.

In the context of a canon, the original melody serves as a model for the subsequent voices, which follow along in a staggered manner. The idea of replication can take various forms, such as beginning at different times or pitches, adding layers of complexity to the piece. Famous examples of canons include Pachelbel's "Canon in D," where the theme is echoed in different voices, enhancing the musical experience through this technique.

Other options, while relevant to musical composition, do not specifically define the process of repeating an entire theme in another voice. For instance, a sequence refers to the repetition of a motif at different pitch levels without necessarily introducing other voices. Imitation involves a similar concept but may not necessarily include the structured texture that a canon provides. A pedal point is a sustained note around which harmonies change, rather than a theme's replication in different voices. Thus, "Canon" succinctly captures the essence of the asked condition