Correct option is C
A
comparator is a precision measuring instrument used to compare the dimensions of a part with a standard reference. It is typically used for checking small deviations in size. Comparators are classified based on their working principles, and the types include
optical, pneumatic, hydraulic, and mechanical comparators.
A
manual comparator is
not a recognized type in metrology since comparators work on an automatic comparison principle, using either mechanical, fluidic, or optical means for precision measurements.
