Finish each of the following sentences in such a way that it means the same as the sentence printed before it.
Scientists have tried very hard to find a cure for this disease.
A.Enormous effort has been made to find a cure for this disease.
B.Enormous efforts has been made to find a cure for this disease.
C.Enormous effort had been made to find a cure for this disease.
D.Enormous effort made to find a cure for this disease.