This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
[{'content': 'The following modes of ventilation may be used for weaning off patients from mechanical ventilation except – \nSelect and explain. \nA. Controlled mechanical ventilation (CMV), B. Synchronized intermittent mandatory ventilation (SIMV), C. Pressure support ventilation (PSV), D. Assist–control ventilation (ACV)', 'role': 'user'}, {'content': 'Answer: A \nExplanation: It is possible to wean patient in any mode of ventilation except control mode ventilation.', 'role': 'assistant'}]