Q.The instrument used to measure blood pressure is

Step 1. A stethoscope (option a) is used to listen to internal body sounds such as the heartbeat and breathing, but on its own it does not produce a pressure reading.

Step 2. A haemocytometer (option b) and a haemoglobinometer (option d) are laboratory tools used to count blood cells and estimate haemoglobin content respectively - neither measures pressure.

Step 3. The sphygmomanometer (option c) is specifically built to measure blood pressure: an inflatable cuff wrapped around the upper arm is connected to a mercury column, dial, or digital sensor, and as the cuff is inflated and then slowly deflated, the systolic and diastolic pressures are read off the sounds of returning arterial blood flow (heard with a stethoscope) or detected electronically.

Step 4. So among the four options, only the sphygmomanometer is designed to measure blood pressure.

Match each option's actual clinical function to the question - only the sphygmomanometer measures pressure.

• Confusing the stethoscope (used alongside the sphygmomanometer to hear the pulse sounds) with the instrument that actually produces the pressure reading.
• Mixing up the haemocytometer/haemoglobinometer (blood-cell and haemoglobin tools) with a pressure-measuring device.