seven countries sighed a treaty binding each of them to perform specified actions on a certain fixed date,with the actions of each conditional on simultaneous action taken by the other countried .each country was also to notify the six other countries when it had completed it action.

the simultaneous action provision of the treaty leaves open the possibility that

C,each country might have a well-founded excuse ,based on the provision ,for its own lack of compliance.

正确答案是C。

感觉没看明白题干，它的逻辑漏洞究竟在哪里呢？

七个国家签署条约，条约规定同一天同时采取行动，行动完成互相通知。问条约没有把什么情况考虑在内。

c说各国都有很好的借口不采取行动。（应该是条约强调simultaneously，这里说不能实施就行了）