What are the signs of an obstructed airway in an adult?

The signs of an obstructed airway in an adult include the inability to talk, dyspnea (difficulty breathing), stridor (a high-pitched wheezing sound indicating an obstruction in the airway), and cyanosis (a bluish tint to the skin indicating inadequate oxygenation).

These signs reflect a critical condition where the airway is partially or fully blocked, and they necessitate immediate intervention. The ability to talk is usually a sign of a clear airway, indicating there is no obstruction, making the first option incorrect. Similarly, full breath sounds and speaking in full sentences, as mentioned in the third option, imply that the airway is clear and unobstructed. Normal respiratory rates and a clear airway, as seen in the last option, also indicate there is no obstruction present. Therefore, the signs listed in the correct answer provide clear indications of a potentially life-threatening situation that requires prompt attention.