A cadenza is a passage of music, contained within the last phrase of a classical work which calls for a soloist or a small ensemble, usually in a "free" rhythmic style, and often allowing virtuosic display. A cadenza usually occurs over the final or penultimate note in a piece, or over the final or penultimate note in an important subsection of a piece.
I would say the correct answer is C. the cadenza. Cadenza is defined as "<span>an </span>improvised<span> or written-out </span>ornamental passage<span> played or sung by a </span>soloist<span> or soloists,' so you can see that the important part of the cadenza is that it is improvised. It is used to show the skill of the performer.</span>
