What is a common method to initiate an IED?

The choice that encompasses all methods of initiating an IED is indeed the most comprehensive option. Each of the methods listed—remote control devices, manual triggers, and timers—represents common techniques used by individuals to activate improvised explosive devices.

Using a remote control device allows the operator to detonate the device from a distance, which increases safety for the person triggering the IED and can be done via mobile phones, radios, or even sophisticated remote control units. Manual triggers typically involve something like a pull system or a switch that requires direct interaction, making it a hands-on method of initiation. Timer mechanisms are engineered to detonate the device after a predetermined amount of time, allowing the perpetrator to place the device and escape before it goes off.

Since all these methods are widely recognized in the context of initiating IEDs, the inclusion of all options in a single answer captures the full scope of techniques employed in such attacks, making it the correct choice.