如图所示，环形导线中通有顺时针方向的电流I，则该环形导线中心的磁场方向为（   ）

古诗赏析 。
                                                                                                                                               伤桃源薛道士
                                                                                                                                                     刘禹锡
                                                                                                                             坛边松在鹤巢空，白鹿闲行旧径中。
                                                                                                                              手植红桃千树发，满山无主任春风。