Ontario Security Guard License Practice Test 2026 – Comprehensive All-in-One Guide for Exam Success!

The correct answer is "10-4." This code is universally recognized—especially in the context of radio communication—as a two-way radio language meaning “Acknowledgement,” “Understood,” or “I understand.” It falls within a system known as 10-codes or ten signals, which are traditional brevity codes used by law enforcement and other public safety professionals (including security guards) during voice communication. In the case of "10-4", the "10" prefix indicates it's a general code, and the "4" denotes acknowledgment or understanding. Therefore, if a security guard in Ontario, or anywhere else, uses 10-4, they are essentially saying "I understand" or "Acknowledged".