Patients under general anesthesia require:

Patients under general anesthesia often experience a state that significantly suppresses their natural physiological responses, which can lead to compromised breathing patterns. To ensure that oxygenation and ventilation are maintained during the procedure, mechanical ventilation may be necessary. This is because general anesthesia can impair the patient's ability to breathe spontaneously and adequately exchange gases.

During general anesthesia, the airway reflexes are diminished, and the patient is typically unable to protect their airway, which increases the risk of aspiration. Therefore, anesthesia providers prepare for the possibility of mechanical ventilation to maintain adequate ventilation and prevent complications. The use of controlled ventilation allows for optimal management of the patient's airway and ensures that oxygen levels remain stable during surgery.

The other choices do not accurately reflect the realities of a patient under general anesthesia. Patients do not have full sensory awareness; rather, they are rendered unconscious. Additionally, the ability to respond and normal breathing patterns are not present, necessitating the support that mechanical ventilation provides.