Which technique should be used to open an airway in an unresponsive patient suspected of having a neck injury?

The modified jaw-thrust maneuver is the appropriate technique for opening the airway in an unresponsive patient who is suspected of having a neck injury because it helps minimize movement of the cervical spine. This is crucial in situations where there is a risk of spinal injury, as improper movement could exacerbate the injury and potentially lead to paralysis.

By using the jaw-thrust maneuver, the rescuer can lift the jaw forward without tilting the head, thus maintaining spinal alignment while ensuring that the airway remains open. This technique is especially important in patients who are unresponsive and may have compromised airway patency due to their condition.

The other techniques listed, while useful in different scenarios, are not suitable for this specific situation involving a potential neck injury. For instance, the head-tilt/chin-lift technique involves extending the neck and can increase the risk of movement at the cervical spine. An oropharyngeal airway requires the head to be tilted back, which also poses a risk of spinal alignment issues in suspected neck injuries. Similarly, a nasopharyngeal airway is not advisable with potential neck injuries, as it can cause trauma to the nasal passages and potentially exacerbate any existing injury.