"What?!" Luna's exclamation isn't quite a shout, but the sharp rise in pitch conveys her shock well enough. She's quiet for a second, briefly embarrassed by the outburst, and quiets down for her next question - although her disbelief is still very much evident. "Um, what do you mean by center of attention? How long is it until the arena's finished?"

There's a couple other questions hidden in those, most of which she doesn't know how to ask. Things like "What if I'm not prepared for attention?" and "What happens if I'm not good enough?" Being the center of attention is pretty much the opposite of what Luna ever expected for herself, and the sudden turn is a little disorienting. It's enough that she almost forgets the mention of trees in the arena, and the things that fact might imply. Things are a little hard to put together right now...