Answer:
performing a sting operation.
Step-by-step explanation:
A sting operation is an undercover investigation process where the police officer/investigator pose as a potential criminal to apprehend the targeted suspect. Most of the times, these officers solicit the suspected criminals to perform crimes by posing as criminal partners or potential victims.
Therefore, if an undercover police officer who in order to obtain proof of solicitation to commit murder, tells the suspect that he will murder her husband for an agreed sum of money, the officer is performing a sting operation.