Final answer:
The use of a fixed melody in one voice was a compositional technique found in sacred Renaissance motets.
Step-by-step explanation:
The statement is true. The use of a fixed melody in one voice was a compositional technique found in sacred Renaissance motets. Motets were sacred vocal compositions typically written for multiple voices. While motets often featured polyphony and elaborate counterpoint, they also employed a technique called cantus firmus, where one voice sang a pre-existing melody while the other voices created intricate harmonies around it. This technique created a sense of unity and structure within the composition.