The fire-fighters made every effort to put off the flames. The building

A. The building burned down completely though the fire-fighters made every effort to put off the flames. 

B. Had it not been for the fire-fighters’ every effort, the building would have burned down completely. 

C. Making every effort to put off the flames, the fire-fighters completely burned down the building. 

D. Since the fire-fighters made every effort to put off the flames, the building burned down completely.