You Currently Work as a Machinist in a Factory

Multiple Choice

You currently work as a machinist in a factory. Your salary is $15 per hour. You are thinking about quitting your job and going back to college. It will take you two years to obtain your college degree. Tuition and other costs of the education will total $21,000. You spent $9,000 preparing to be a machinist. In considering whether to go back to school, the $9,000 of prior training is a(n) :

A) Differential cost
B) Sunk cost
C) Variable cost
D) Opportunity cost