Apparatus to measure rate of respiration and R.Q. is

Answer: Option C

Apparatus to measure the rate of respiration and R.Q. is Respirometer.
A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide.
Respirometers are used primarily to perform intermittent measurements of tidal and minute volume and are most widely used to assess that mechanical ventilators are delivering an appropriate volume of gas.