A.Chef A is correct.
To give the soup an added or contrasting flavor and also for presentation of the soup so that it can be appealing to the guest.
If this helps
A dominant chord is a major triad built on the fifth scale degree of either a major scale or a minor scale. Major triads consist of a root note, a major third, and a perfect fifth. ... A simple D major triad contains the notes D, F♯, and A. This chord becomes a dominant seventh chord (V7) by adding the note C.
