Final answer:
The Bag-valve-mask device (C) is contraindicated in patients with blunt thoracic trauma.
Step-by-step explanation:
In patients with blunt thoracic trauma, the use of a Bag-valve-mask device (C) is contraindicated. This device requires positive pressure ventilation, which can potentially worsen the injury by causing the lungs to overinflate and increase the risk of pneumothorax or other complications.