When advised of a 10-13 alarm, what radio signal code should the calltaker input into the system?

The correct choice for a 10-13 alarm is the radio signal code 13X1. This code specifically designates a "10-13" call, which is used to indicate a department-wide alarm or critical incident. The 13X1 code allows the dispatcher to clearly identify and prioritize the alarm situation within their system, facilitating a quicker response from patrol units and other emergency services.

Using the appropriate code ensures that all responding units are aware of the nature of the alarm and can prepare accordingly. It is important for calltakers to use standardized codes for clarity and efficiency in communication to maintain the safety of officers and the public during critical incidents.