The correct answer is A) Only a trained person should attempt to insert an airway tube. Inserting an airway tube is a medical procedure that requires proper training and skill to perform safely and effectively. Untrained individuals attempting to insert an airway tube could potentially cause serious harm to the victim, such as damage to the throat or airway. Airway management is a critical skill that should only be performed by those who have received the necessary medical training and certification. The other options are incorrect because: B) Improper insertion of an airway tube can indeed damage the victim's throat, C) Inserting an airway tube does not prevent vomiting, and D) The correct size of airway tube depends on the victim's anatomy and should be determined by a trained medical professional.