choice about subjunctive mood

[DiZ806]

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


I know A is right but I do not know why B is wrong?
Just because B does not use subjunctive mood?
If you say B is wrong because of mood,I have to point that we can choose and not about mood( some case express hypothesis but we do not use subjunctive mood to express)
.in addition B is simplified than A..............
How should I decide? Who can tell me why B is wrong?

[RonPurewal]

please search the forum before posting.

post56234.html#p56234