The correct answer would be 2. An electrocardiogram provides a graphic record of the heart's electrical activity at rest or during exercise, so it would be best suited to detect dysrhythmia, a disturbance in the heart's rhythm.
A pulmonary artery catheter monitors cardiovascular pressures in the pulmonary artery.
An intracranial pressure monitor consists of a small plastic tube usually inserted in the brain's left or right anterior portion to monitor and assess the pressure surrounding the brain of patients who have sustained head trauma, brain hemorrhage, brain surgery, or conditions in which the brain may swell.
A pulse oximeter is an instrument that uses a light-emitting diode, a photodiode signal detector, and a microprocessor to determine the percentage of oxygen saturation of arterial blood.