Final answer:
The correct answer is A. A capella. A capella is a musical performance in which a lead singer is joined by other singers unaccompanied by instruments and the tempo is slow.
Step-by-step explanation:
The correct answer is A. A capella. A capella is a musical performance in which a lead singer is accompanied by other singers but no instrumental accompaniment is present. The tempo of an a capella performance can vary, but it is often slower to allow for the harmonies and vocal arrangements to be heard clearly.