Select the word-pair that best represents a similar relationship to the one expressed in the given pair of words. (The words must be considered as meaningful English words and must not be related to each other based on the number of letters/number of consonants/vowels in the word)

Thermometer : Temperature

Oximeter : Oxygen level of blood

Thermometer : Temperature

The logic followed here is :

Thermometer is used to measure the temperature

Similarly

Oximeter : Oxygen level of blood

Oximeter is used to measure the Oxygen level of blood