Answer: a unilateral contract that Lana can accept by passing the exam.
Explanation:
A unilateral contract is a form of contract agreement whereby the offeror promises to do a particular thing or pay a certain amount after a specified action has occured.
In this scenario, Metro City would only give an employment offer to Lana if she passes her exam. This is a unilateral contract that Lana can accept by passing the exam.