Final answer:
The concerted madrigal differed from earlier madrigals in that it included instrumental accompaniment, all voices contained similar rhythm, and it was designed for performance. c is correct.
Step-by-step explanation:
The concerted madrigal differed from earlier madrigals in several ways. One of the main differences is that the concerted madrigal included instrumental accompaniment (option a). This means that in addition to the voices, there were instruments playing along with the singing. This added a new layer of sound and texture to the music.
Another difference is that all voices in the concerted madrigal contained similar rhythm, moving together (option b). This created a more unified and synchronized sound.
Additionally, the concerted madrigal was designed for performance, to be heard rather than sung (option c). This means that it was meant to be performed in a public setting, such as a concert hall, rather than sung privately in a small group or choir.
In conclusion, the concerted madrigal differed from earlier madrigals by including instrumental accompaniment, having all voices contain similar rhythm, and being designed for performance.