Which of the following best describes eavesdropping under unlawful conditions?

Eavesdropping under unlawful conditions is best described by the use of surveillance without consent. This activity involves secretly listening to or monitoring conversations without the knowledge or permission of the involved parties. In the context of privacy laws and ethical standards, such actions are deemed illegal because they violate the right to confidentiality and trust in personal or professional communications. The focus on consent highlights the distinction between lawful surveillance, which may occur under regulated circumstances, and unlawful eavesdropping, which disregards individual privacy rights.

In contrast, listening to conversations legally typically involves situations where consent is given, such as public discussions or monitored communications with prior authorization. Recording public statements does not fall under eavesdropping as it pertains to information that is openly shared in a public forum. Similarly, using listening devices for personal gain implies a motive beyond mere surveillance and may also suggest illegitimate intentions, but it does not directly address the legality of the act itself. Therefore, the unconsented use of surveillance is the most accurate description of eavesdropping under unlawful conditions.