Fourteen applicants for a city of Providence, Rhode

Island, police academy training class each received

from the city a letter stating that it was a "conditional

offer of employment" subject to successful completion

of medical and psychological exams. The 14

applicants passed the medical and psychological

exams. However, these applicants were replaced by

others after the city changed the selection criteria.

Can you identify an offer and acceptance in this case?

Can you make out a bilateral or unilateral contract?