Answer:
usually in A B A form
Step-by-step explanation:
I would have said (a) because an aria is air, melody, and tune specifically: an accompanied, elaborate melody sung (as in an opera) by a single voice enjoyed by the soprano's romantic aria.
So it wouldn't be the others because aria is like solo so it wouldn't be (d),(c) would not be it either because opera is like an aria as well, and finally (b) because aria overall focuses on emotions when the soloist changes their voice/s.
Hope this helps.
Best of luck.