Why are girls required to wear One piece swimsuits in school swimming? (10 points)?

I am thinking of starting a petition for my school to allow girls to wear two piece swimsuits. I ASSUME that we are currently required to wear a one piece because it s "Modest" and won t be too "Distracting" But I feel like it s wrong that boys can show their entire upper body and if we show our backs or stomachs it s considered too revealing? I feel like it s a prime example of sexualization (Not to say there isn t sexualization towards males also, this issue just applies to myself). I want to know if you know why this rule is in place so can further study the topic.