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: Dental
Pulse oximetry is used in: 
Select and explain. 
A. Blood volume, B. Blood coefficient, C. Laser wavelength for estimation of blood flow, D. Probe with diode is used to measure oxygen saturation
D: Probe with diode is used to measure oxygen saturation
Answer: D: Probe with diode is used to measure oxygen saturation 
Explanation: Pulse Oximetry is a non-invasive method to measure the oxygen saturation levels during the administration of anesthesia or other medications with the help of a finger, ear, or foot probes.
The pulse oximeter sensor consists of two light-emitting diodes, one to transmit red light (660 nm) and the other to transmit infrared light (940 nm), and a photodetector on the opposite side of the vascular bed. 
The light-emitting diode transmits red and infrared light through a vascular bed such as the finger or ear.

Ref: Grossman’s endodontics, 13th edition, pg no:76