Which method can be used to activate a victim-operated IED utilizing ambient environmental factors?

The method of activating a victim-operated IED (Improvised Explosive Device) through ambient environmental factors emphasizes the use of infrared detection. This technique relies on the presence of infrared radiation, which can be emitted by warm bodies or objects in the environment. When a person approaches or passes by the IED, the infrared sensor could detect the change in heat signature. This makes infrared detection particularly effective in scenarios where the device is designed to trigger upon sensing the warmth of a human body, making it a stealthy and undetectable method of activation.

Other methods, while also capable of functioning in specific contexts, do not align as directly with the ambient environmental factors needed for this type of activation. For instance, mechanical pressure typically requires a physical action, such as stepping on a trigger, while sound and heat sources may involve more active participation from the victim rather than a passive environmental factor. In contrast, infrared detection uses the ubiquitous presence of heat from living beings to trigger the device, which is what makes it the most suitable choice for this context.