Lanza was just hired to work for a government defense contractor. A clause in the contract calls for Lanza to pass a background check before he can work in the job, as a security clearance is required for all employees. If he cannot pass the background check and get appropriate security clearance, he cannot have the job and the employment contract will be voided. This clause would be a

a. condition precedent

b. concurrent condition

c. condition subsequent

d. nothing of consequence since Lanza has already signed the contract and the employer may not breach.

Please explain why other options is incorrect..