GMAT sentence correction英語題

Not one of the potential investors _____________ not to be concluded.

(A) is expected to make an offer to buy Frist 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

答案點解係 (A)?

"the deal"唔係singular noun 嗎, 點解會跟"were".

請指教, thanks!