Sanguine, meaning positive or optimistic, is a fitting term to describe Paris, the City of Lights, because it is often associated with positive images like the Eiffel Tower, cafes, and romance.
The other terms are unfitting because of their definitions.
Melancholic means depressive, choleric means irritable, and phlegmatic means stoic. Since Paris is considered beautiful and positive, melancholic and choleric do not work. Phlegmatic doesn't work because Paris is often heavily associated with deep feelings of passion, love, and lust.
Hope this helps!
