What device is a flexible sheet of plastic that becomes semi-rigid when folded around a patient?

The correct choice is a SKED stretcher, which is designed specifically for confined space rescues and similar challenging environments. This flexible device is made from a durable, lightweight material that can easily conform to the shape of the patient when they are placed on it. When the SKED stretcher is wrapped around the patient, it becomes semi-rigid, providing support and stability while still allowing for some flexibility. This characteristic is essential in confined space situations, as it facilitates safe lifting and transport of injured individuals without exacerbating their injuries.

Moreover, the SKED stretcher’s design allows it to be used in various positions, making it versatile for different rescue scenarios. When compared to other options, it stands out for its ability to adapt to the patient's body and the context of the rescue, ensuring that the patient is secured and protected during the extraction process.