【开放英语4(英语II(2))-1162网上形考机考题库】 — Good morning, may I speak to Mark, please

【开放英语4(英语II(2))-1162网上形考机考题库】 — Good morning, may I speak to Mark, please?
— _________.
A. Who’s there?
B. Who’s speaking?
C. Who are you?
D. Who wants to speak to Mark?