Critical Reasoning

Seven countries signed 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 countries. Each country was also to notify the six other countries when it had completed its action.

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

(A) the compliance date was subject to postponement, according to the terms of the treaty
(B) one of the countries might not be required to make any changes or take any steps in order to comply with the treaty, whereas all the other countries are so required
(C) each country might have a well-founded excuse, based on the provision, for its own lack of compliance
(D) the treaty specified that the signal for one of the countries to initiate action was notification by the other countries that they had completed action
(E) there was ambiguity with respect to the date after which all actions contemplated in the treaty are to be complete

why C and why is not B i dont understand...

(B) one of the countries might not be required to make any changes or take any steps in order to comply with the treaty, whereas all the other countries are so required -- It is talking about obligation on other countries which is not specified , the option os fine till it restricts to one of the countries but when it says all other countries , no rules are mentioned for any obligation on countries together , its about rules to followed as an individual country.

(C) each country might have a well-founded excuse, based on the provision, for its own lack of compliance --- This option talks with reference to each country which is in sync with the argument .

IMO C.