Choose one sentence that has the same meaning as the root one:
Unless you are more hard-working, I will sack you.
A.                                        I will be sack you providing that you are more hard-working.                                                                                                                                                            
B.                                        Be more hard-working otherwise I will sack you.                                                                                                                                                            
C.                                        Suppose you are more hard-working, I will sack you.                                                                                                                                                            
D.                                        Because of your being hard-working, I will sack you.