An Example of a Whistleblower (In Relation to Ethics) Would

An example of a whistleblower (in relation to ethics) would be a(n) :

A) security guard who sends notices to employees who drive too fast in the company parking lot.
B) executive who imposes fines on employees who behave unethically.
C) company specialist conducting training programs about ethics.
D) bookkeeper who tells a journalist about fraudulent accounting in the company.