Answer :
Final answer:
The missing option to complete the sentence is Capillary tube. Capillary tubes can be used for pressure indication as they rely on the principle of capillary action.
Explanation:
The missing option to complete the sentence is B) Capillary tube. Capillary tubes can be used for pressure indication as they rely on the principle of capillary action. This is when a liquid in a narrow tube moves upwards against gravity due to adhesion and cohesion forces. Pressure can be determined by measuring the height of the liquid column in the capillary tube.
For example, a liquid-filled manometer, which is a type of manometer that uses a U-shaped tube with one side open to the atmosphere, can indicate pressure using a capillary tube. The pressure difference between the two sides of the U-shaped tube causes the liquid to rise or fall in the capillary tube, providing a visual indication of pressure.
