Final answer:
Dame Joan Sutherland was known for her performances in the trilling style known as Coloratura, which is the correct answer to the student's question (A) Coloratura.
Step-by-step explanation:
Dame Joan Sutherland was acclaimed for her roles in the trilling style known as Coloratura, from the Italian for coloring. This style, which is categorized by elaborate vocal embellishments and a high register, fits option A) Coloratura.
While 'Bel canto' refers to a style of singing that emphasizes beautiful tone and technique, 'Soubrette' is a character type often portrayed as a lively, clever maid in opera and theatre. 'Dramatic' is a vocal style that's powerful and with a strong emotional delivery suited to operatic roles that require a significant vocal weight and vigor. Therefore, the answer to the student's question is A) Coloratura.