Which of the following best describes a probable cause in wiretapping?

Probable cause in the context of wiretapping refers to the legal standard that requires law enforcement to have adequate reason to believe that an individual is involved in criminal activity before obtaining a warrant for surveillance. The correct choice indicates that there must be strong evidence suggesting that a crime is currently occurring, which serves as a justification for intrusive measures like wiretapping.

This standard is designed to protect individuals’ privacy rights, ensuring that they cannot be surveilled based merely on conjecture or unfounded suspicions. Hence, for authorities to justify the action of monitoring someone's communications, they need more than just a hunch; they need compelling evidence that strongly indicates ongoing criminal conduct. This could involve witness statements, illicit transactions observed, or other forms of corroborative evidence demonstrating that the crime is indeed happening. Overall, strong evidence is necessary to balance law enforcement efforts with respect for civil liberties.