Adventures in Shelving - Part Letter T

Mustachioed Patron: Excuse me, do you work here?
Bianca: [nods]
Mustachioed Patron: Well, I haven't been here in a while, and I was looking for the card catalog - so that I can look up a book. Can you tell me where the card catalog is?
Bianca: __________________________________________

Guess my answer:

A) Hmm...actually, I don't think we have one anymore. I think it's all electronic now.
B) Um yeah, I think they call it a computer?
C) Card catalog? [laughs] What's that?
D) Card catalog?! Go back to the Stone Age!

...now guess which one I wanted to say.