When a girl asks you if you find another girl pretty?

My crush was talking about my friend's new girlfriend at school today. (She never saw the girl) then she just asked me if his girlfriend was pretty..I said yes. We almost never talk to each other but she just asks me random questions like that sometimes, what does it mean and what should I say next time?

PS: she is just a crush and I am not even sure she likes me yet cause I'm really shy and this is going nowhere for now.
When a girl asks you if you find another girl pretty?
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