Measuring Blood Pressure
Blood pressure is measured using a device called a sphygmomanometer (Greek sphygmos = “pulse”). It consists of an inflatable cuff to restrict blood flow, a manometer to measure the pressure, and a method of determining when blood flow begins and when it becomes impeded. Since its invention in 1881, it has been an essential medical device.
Q. The word its refers to …
D is correct because, although the subject to which it refers is not in the same or previous sentence, the entire passage is about the sphygmomanometer. The device to which the pronoun referent refers back to is mentioned in the first sentence which is two sentences before. In this case, reading the sentence after can confirm the answer because the subject, “sphygmomanometer”, is mentioned again. Option a is incorrect because it is not a specific object. Options b and c are wrong because they are just parts of the device which is the subject.