Which of the following forms was commonly used during the Renaissance period?

The form that was commonly used during the Renaissance period is the Mass. This significant form of liturgical music was essential in the context of the church, where composers would set the texts of the Mass Ordinary (which includes the Kyrie, Gloria, Credo, Sanctus, and Agnus Dei) to music. The Mass evolved during the Renaissance, showcasing intricate counterpoint and harmonies that reflected the period's artistic values. Composers like Josquin des Prez and Giovanni Palestrina are well-known for their contributions to this genre, using polyphony to enhance the spiritual experience.

In contrast, while opera began to emerge toward the end of the Renaissance, it did not become a fully developed form until the Baroque period that followed. Symphonies and rock ballads did not exist during the Renaissance. The symphony arose in the late 17th to 18th centuries, and rock ballads are a modern genre stemming from the 20th century. This context highlights why the Mass is the most appropriate answer concerning Renaissance musical forms.