It is a ________ the women holding a baby are first offered seats on a bus．

It is a ________ the women holding a baby are first offered seats on a bus．

A.rule

B.practice

C.measurement

D.demand

答案及解析： B

解析：

抱孩子的妇女优先就座，这是一种社会道德的约定俗成，不是硬性的规矩。