From the information given in the question, we can infer that we need to check for such a relationship where the instrument is being used to measure the physical quantity. ( since Barometer is being used to measure atmospheric pressure.) In option A, the unit of force is given as , which is not a correct relationship. Richter scale is used to measure the strength of earthquakes, but in the option, it is linked to heat. Therefore, option B is not correct. The weighing scale measures the weight of an object, whose unit is . Hence, this is wrong. The thermometer measures temperature, which is the correct relationship. The correct option is D.