Which Statement Is NOT an Illustration of Opportunity Cost

Which statement is NOT an illustration of opportunity cost?

A) If a person takes a job as long-distance truck driver, he won't have as much time to spend with his family.
B) If a person studies for her English class, she won't have as much time to write creative poetry.
C) The more a person works at her job, the more leisure time she has.
D) If I party every night of the week, my grades at school will drop.