The camiseta thing has been bothering me for a while because one would not necessarily call every top that lacks a collar or buttons a t-shirt so, I tried the word "top." DuoLingo accepts it. I feel so much better. You might too.
Earlier in this level it accepts tops for camisetas! but not in this case for some reason. It gives vest as a correct example - whoever would say do you have pretty vests???? And in this post it is saying T-shirts - at least that's ok.
Is it possible 't-shirts' means something different in Spanish than English? In American English 't-shirts' are generally knit jersey with silk screened images, often in men's sizes. Something I have NEVER described as PRETTY!