A customer blames you for a mistake that was clearly the customers fault. The customer has even gone so far as to complain to your manager. You can prove that it was the customers error and not your own that caused the problem. In this situation, you would be most likely to

(a) apologize to the customer and explain what happened

(b) apologize to the customer and fix the problem

(c) forward the proof to your manager to make sure your side of the story is also noted

(d) suggest that you and the customer meet together with your manager to discuss and resolve the issue