Which of the Following Does Not Illustrate the Concept of Opportunity

Which of the following does not illustrate the concept of opportunity cost?

A) Between 1990 and 1997,the state of California laid off 10,000 of its university employees to have the money to hire 10,000 employees for its prison system.
B) By reducing its unemployment rate,the United States dramatically increased its production of both civilian and war goods in the early years of World War II.
C) A computer whiz at M.I.T.gives up her senior year at the university to take a high-paying position at a new company,Socrates.com.
D) The Secretary of the Interior must choose between enforcing a law that would save the spotted owl,an endangered species or the loss of 500 logging jobs.