Answer :
Feeler gauges are used to measure the gap between a straight edge and a given surface, as they consist of thin metal strips with precision thickness, hence the correct option is (a) feeler gauges.
The gap between the straight edge and a given surface can be measured using feeler gauges. Feeler gauges consist of a set of thin metal strips with measured thicknesses, which are used to determine the size of small gaps. While other tools like dial bore gauges, split ball gauges, and dial indicators are used for different types of precision measurements, feeler gauges are the simplest and most direct tool for measuring gaps.
