[单选题]( )S1:MAYDAY,MAYDAY,MAYDAY, This is MV Blue Sky. I have collided with an unknown object. I am sinking. Over. S2:MV Blue Sky, this is Eastern station. Report your position. Over. Q:What has happened to MV Blue Sky? A.She has run aground B.She has collided with a ship C.She has collided with an unknown object D.She has struck an iceberg