阅读下面这首小令，完成小题。
                                                                                                   天净沙·春
                                                                                                  【元】白朴
                                                                                                春山暖日和风，
                                                                                                阑杆楼阁帘栊，
                                                                                                杨柳秋千院中。
                                                                                                啼莺舞燕，
                                                                                                小桥流水飞红。
     【注释】① 帘栊：带帘子的窗户。②飞红：花瓣飞舞，像落花。

下面哪些图形是轴对称图形．（   ）