What does "ad libitum" allow musicians to do?

"Ad libitum" is a term that indicates a degree of freedom in the performance of a piece of music. When musicians see this instruction, it means they are allowed to interpret the music in a less rigid manner, giving them the liberty to play certain passages with flexibility. This can include making choices about timing, rhythm, and embellishments, allowing for personal expression and spontaneity in their performance.

In the context of the provided choices, this concept of freedom aligns perfectly with the ability to play passages freely, enabling artists to make interpretive decisions based on their artistic judgment or the context of their performance. The other options involve specific elements of performance that do not correspond with the essence of "ad libitum," which is all about embracing flexibility rather than adhering to strict guidelines or interpretations.