Joe Lawschool just graduated from law school and has taken the California bar exam (the licensing exam to practice law in California). He got a job at Grumpy, Stuffy, and Stodgy law firm. The employment contract states that he has one year to pass the bar exam or he will no longer be employed. This condition in the contract would be classified as:

A. A concurrent condition
B. A condition subsequent
C. An implied condition
D. A condition precedent