Speaker A: The open stack system is marvelous. I love to browse around and just see what b

Speaker A: The open stack system is marvelous. I love to browse around and just see what books there are. Speaker B: ______

A．So do I. But I"ve found you can waste a lot of time that way.

B．I don"t know when they started to introduce this new system.

C．I wonder why they don"t add more books on economics to the stacks.

D．What do you think of the service of the librarians？

请帮忙给出正确答案和分析，谢谢！