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