Q. With reference to pulse oximeter, consider the following statements:
1. It has a pair of LEDs – one emitting green light and another blue light.
2. It can be attached to the fingertip, earlobe or toes.
3. It calculates the amount of oxygen in blood using Oxygenated and deoxygenated haemoglobin.
Which of the statements given above is/are correct?

[A] 1 and 2 only

[B] 2 and 3 only

[C] 1 and 3 only

[D] 1, 2 and 3

Answer: B
Notes:

Statement 2 and 3 are correct. 

Statement 1 is incorrect: The oximeter has a small electronic processor and a pair of LEDs – one emitting red light and another infrared. 

Source : Indian Express