how often do you do to the park?A.once B. ten days C. for fix days D. after a month

how often do you do to the park?A.once B. ten days C. for fix days D. after a month
此题选择什么啊,怎么解释呢?谢谢各位帮友哦
我也觉得这题有误，但题目就是这样的……