Which of the Following Statements Described the Activities of a Whistle-Blower

Which of the following statements described the activities of a whistle-blower?

A) Mattel employees were sorry that 150 of the 10 million Power Wheels cars and trucks the company sold had caught on fire.
B) Mattel research engineers proved that the spate of fires in the company's Power Wheels cars and trucks was the result of consumers' tinkering with the engine.
C) One of the Mattel Power Wheel cars that caught on fire and slightly burned its rider was owned by a former Mattel employee.
D) A Mattel engineer who worked on the Power Wheels cars knew that they were prone to catching on fire and reported this to a consumer watchdog group.