Kinda plain and simple, but that honestly does track with her impression of Waver. He's always seemed a pretty pragmatic type, really.

"Tea sounds good."

Coffee would be fine, too, but that's more a breakfast and stimulant beverage, not a meal beverage. That said, Ritsuka's taking a moment to have a look at those books first while she waits, sheer curiosity getting the better of her.