The correct answer is B. In option B, the data capture system of Firm W fails to capture the correct market rates, leading to derivative trades being executed at incorrect prices and resulting in significant losses. This scenario directly illustrates a loss caused by an operational risk, which is the focus of the question. Operational risk arises from inadequate or failed internal processes, people, systems, or from external events. In contrast, options A and C describe losses resulting from market risk exposure, where changes in market variables such as interest rates or commodity prices impact financial instruments. Option D describes a credit risk exposure, where a counterparty fails to fulfill a legal obligation to settle a debt. The explanation provided in the file content clearly distinguishes operational risk from market and credit risks, emphasizing the importance of identifying and assessing operational risks through appropriate tools and processes as outlined in the "principles for the Sound Management of Operational Risk" by the Basel Committee on Banking Supervision.