input: The following are multiple choice questions (with answers) about medical knowledge.   **Question:** A patient is undergoing MRND for laryngeal malignancy; while dissecting the venous tributaries the surgeon elevated the internal jugular vein for ligation. Suddenly the patients EtCO2 dropped from 3g mmHg to 12 mmHg and the patient developed hypotension along with cardiac arrhythmia. Which of the following is most likely cause??   (A) Sympathetic overactivity   (B) Vagal stimulation   (C) Venous air embolism   (D) Carotid body stimulation
output: ['(C) Venous air embolism <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Sympathetic overactivity  (B) Vagal stimulation  (C) Venous air embolism  (D) Carotid body stimulation <> possible answers', '  A patient is undergoing MRND for laryngeal malignancy; while dissecting the venous tributaries the surgeon elevated the internal jugular vein for ligation. Suddenly the patients EtCO2 dropped from 3g mmHg to 12 mmHg and the patient developed hypotension along with cardiac arrhythmia. Which of the following is most likely cause?? <> context']