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
[{'content': "pulse oxmetry is based on:\nBeers law\nDopplers law\nLambert's law\nPoilles law \nSelect and explain. \nA. 1&2, B. 2&3, C. 1&3, D. 1&4", 'role': 'user'}, {'content': "Answer: C \nExplanation: The principle of pulse oximetry is based on Beer-Lambert law, which states that the concentration of an absorbing substance in solution can be determined from the intensity of Light transmitted through that solution.\nIn other words, arterial oxygen saturation is based on the differential absorption of red and infrared photons by oxyhemoglobin and deoxy-haemoglobin measured by the pulse oximeter.\nThis law is a combination of 2 laws: \n\nBeers law: The intensity of transmitted light decreases exponentially as the concentration of the substance increases.\nLambert's Law: The intensity of transmitted tight decreases exponentially as the distance travelled through the substance increases.", 'role': 'assistant'}]