Correct option is D
A telescopic gauge is used for measuring internal dimensions of holes and bores. It consists of spring-loaded plungers that expand to fit the internal surface, capturing the dimension, which is then measured using a micrometer. It can measure not only circular bores but also slightly irregular internal shapes, making it versatile. However, accuracy depends on the user’s skill. Other options are too restrictive, as the telescopic gauge is not limited to only circular or deep holes.
