路过的进来帮下忙thegirlsdanced___themusi
the girls danc ___the music being played on the radio A with B to C by D of 简要说明理由
选B，确定。 这是fixed phrase,意思是随着音乐起舞。 类似的to的用法还有这样几个： ticket to ...（place） answer to ...（question） key to ...(door) entrance to ...(place)