以下哪种改写，与to_char(order_date,'yyyymm')='201910'的含义是等价的？(注，order_date列为date类型数据）B A order_date between '20191001' and '20191031' B order_date >= to_date('20191001','yyyymmdd') and order_date < to_date('20191101','yyyymmdd') C order_date between to_date('20191001','yyyymmdd') and to_date('20191031','yyyymmdd') D order_date=to_date('201910','yyyymm')