gmat的语法题Not one of the potential investors is expected to make an offer to buy First Interstate Bank until a merger agreement is signed that includes a provision for penalties if the deal were not to be concluded.A. is expected to make an offer to buy First Interstate Bank until a merger agreement is signed that includes a provision for penalties if the deal wereB. is expected to make an offer for buying First Interstate Bank until they sign a merger

gmat的语法题
Not one of the potential investors is expected to make an offer to buy First Interstate Bank until a merger agreement is signed that includes a provision for penalties if the deal were not to be concluded.
A. is expected to make an offer to buy First Interstate Bank until a merger agreement is signed that includes a provision for penalties if the deal were
B. is expected to make an offer for buying First Interstate Bank until they sign a merger agreement including a provision for penalties if the deal was
C. is expected to make an offer to buy First Interstate Bank until a merger agreement be signed by them with a provision for penalties if the deal were
D. are expected to make an offer for buying First Interstate Bank until it signs a merger agreement with a provision for penalties included if the deal was
E. are expected to be making an offer to buy First Interstate Bank until they sign a merger agreement including a provision for penalties if the deal were
划线部分看选项a,这道题我在管卫东31套里做到两遍,但是一套答案是选a,一套答案是选c,我非常的搞不懂,求高人解释里面有几个语法点,谢谢了!