The correct option is A Spirometer
A spirometer is used to measure the values of several lung volumes and capacities, two of which are the inspiratory reserve volume and the expiratory reserve volume.
A sphygmomanometer is an instrument that is used to measure blood pressure.
A stethoscope is used to listen to the sound of the heart beat, lungs, intestines or the blood flow in veins and arteries.
A thermometer is used to measure body temperature.