Which One of the Following Is an Example of a Nondiversifiable

Which one of the following is an example of a nondiversifiable risk?

A) a well respected chief executive of a firm suddenly resigns
B) a well respected chairman of the European Central Bank suddenly resigns
C) a key employee suddenly resigns and accepts employment with a key competitor
D) a well managed firm reduces its work force and automates several jobs
E) a poorly managed firm suddenly goes out of business due to lack of sales