Applicants to a city's police academy training program receive a letter from the city stating that they were receiving a conditional offer of employment subject to their successful completion of medical and psychological exams. The applicants pass the exams. The city then changed the selection criteria and the applicants were replaced by others for the police academy training program. Please explain based on what you learned in the chapter if there is a contract and if so is the contract a bilateral contract or a unilateral contract?