The term 'grating' in metrology means that

Rulings are more closely spaced, producing a periodic pattern without blank gaps

Rulings follow a logarithmic scale

Rulings need not have any pattern

Rulings are spaced relatively far apart, requiring some type of interpolating device to make accurate settings

Solution

Correct option is A

In metrology, the term 'grating' refers to a series of rulings or lines that are closely spaced, producing a periodic pattern without blank gaps. Gratings are commonly used in optical devices, such as diﬀraction gratings, to disperse light into its component wavelengths. The closely spaced rulings create interference patterns that are crucial for precise measurements in various scientiﬁc and engineering applications.