Which body paragraph most skillfully provides details about the adjustment and attempts to regain the customer's confidence

The question is incomplete and the full version can be found online.  

c. We take complaints such as yours very seriously and investigate each and every one carefully. In your case we have come to the conclusion that no fault on your part can be detected. In fact, apparently some piece of machinery in our plant malfunctioned. Rest assured that we have investigated the flaw and addressed it immediately so it won't ever happen again.

Explanation:

Out of the options provided, the one that most skillfully provides details about the adjustment and attempts to regain the customer's confidence is the one that provides information about what the problem was without getting into too many technical details that could highlight the problem and are not really helpful for the customer. At the same time, is important to acknowledge the customer´s frustrations, apologize properly and ensure actions have been taken to provide a better service for the future

with whom will you be coming to the party? this is written correctly.