Which of the following is an example of a radiological dispersal device?

A “dirty bomb” is a prime example of a radiological dispersal device because it is specifically designed to spread radioactive materials in a manner that contaminates an area, potentially causing harm through both the physical explosion and the subsequent radioactive contamination. These devices typically combine conventional explosives with radioactive materials, aiming to disperse those materials over a wide area.

Understanding the impact and function of a dirty bomb is crucial in the context of radiological threats. It highlights the deliberate use of radiation to instill fear and cause disruption, making it distinctively categorized as a radiological dispersal device.

The other choices do not fall under the classification of a radiological dispersal device. Conventional bombs do not contain radioactive materials; X-ray machines are devices used for imaging and do not disperse materials but rather emit radiation for diagnostic purposes; and smoke detectors typically rely on small amounts of radioactive material for their detection capabilities but are not designed to disperse those materials over an area.