Who did the teacher ___ as article for the wall newspaper?

A．has write

B．has written

C．have write

D．have written

如果施工单位与建材商在买卖合同中，既约定了定金，又约定了违约金。在建材商违约时，施工单位( )。

A．可以同时适用定金与违约金的约定

B．只可选择适用其中一项约定

C．只能适用违约金约定

D．只能适用定金约定