Probable cause is defined as:

Probable cause is best defined as a reasonable ground to suspect that a crime has been committed. This standard is a critical concept in law enforcement and legal proceedings, as it provides the necessary basis for police to perform actions such as arresting an individual or conducting a search without a warrant. Probable cause does not require absolute certainty but rather a set of facts or circumstances that would lead a reasonable person to believe that a crime has occurred or is occurring.

The essence of this definition relates to the balance between individual rights and the government's duty to enforce the law, allowing law enforcement officers to act without breaching constitutional protections against unreasonable searches and seizures. Probable cause must be based on factual evidence and reasonable inferences drawn from that evidence, ensuring that law enforcement actions are justified and not arbitrary.

The other options do not accurately reflect the legal definition of probable cause; they either misrepresent the necessary threshold for action by law enforcement or suggest a lack of sufficient evidence or formality.