In which situation would a lease be considered legally unenforceable?

A lease can be considered legally unenforceable if it violates public policy or is improperly executed. Public policy refers to the principle that certain agreements and actions should not be permitted under the law because they conflict with the societal interests or welfare. For instance, leases that involve illegal activities, such as renting for illegal purposes or situations that could expose others to harm, would fall under this category. Additionally, a lease that is not properly executed—meaning it lacks essential elements like a valid signature, description of the property, or agreed-upon terms—would also be unenforceable. Contracts must follow specific legal guidelines for them to be recognized and upheld in court, and any deviation from these can lead to a lack of enforceability.

In comparison, the other options do not inherently affect the enforceability of a lease. Changes made to the terms of a lease by mutual consent do not invalidate it; rather, they can be part of an amendment process. A property being left vacant does not affect the legal standing of the lease itself. Similarly, including a broker's fee in the lease does not make it unenforceable, as it's a common practice in rental agreements, provided it adheres to local laws and regulations.