Which of the Following Is NOT an Example of a Way

Which of the following is NOT an example of a way that people become unemployed?

A) A full-time homemaker starts to look for work after staying at home until her youngest child enters school.
B) Raul is fired and immediately begins looking for another job.
C) Jose retires and begins to receive a pension each month.
D) Mary quits her job and starts to look for another job.