Which of the following italicized parts is used as a subject？A．What do you think has chang

Which of the following italicized parts is used as a subject？

A．What do you think has changed her so quickly？

B．Who do you think the guest professor is ？

C．Where do you think is the cheapest hotel？

D．How often do you think our mother goes to the cinema？

请帮忙给出正确答案和分析，谢谢！