Purple. since the subject has been raised with the DD and she has rejected the suggestion, she is probably capable of considering that possibility herself.
I think it is fair enough to, say, suggest deodorant to a kid entering puberty - sometimes kids don't realise or it doesn't occur to them that they could do something differently - and some kids need to be encouraged to up their hygiene at puberty. But I personally would hate to send my kid the message that the reason they should do anything is to avoid being teased.
I had to take my DSD shopping for bras because she hadn't quite realised that she was as developed as she was (she was measured as a 32DD but hadn't been wearing a bra to school; I don't think she encountered any teasing, but it did concern me; also, I wanted her to be comfortable!) - but if she had said to me "nah, I'm happy to go without", I'd have closed my mouth then and trusted that she was at least now conscious of the decision she was making, and that she'd know she could change her mind later and have my help sorting it out. I would not have said to her "well, you might get teased at school", because I would feel that I was adding to a sense of shame about the female body.
The OP asked her DD, the DD said no, the DD might change her mind and might not. All bases seem to have been covered, really.
Fortunately, not every teenager wants to be a slave to their peers, and sometimes they surprise us by being much more brave about their choices than we'd be ourselves.