There are four vernier scales, whose observations are given in column - I and the correcponding calculations of least count are given in column - II. Match column - I with column - II appropriately. (Here S = value of IMSD : N = Value of number of divisions on vernier) (Assume ideal conditions)
`{:(,"Column - I",,"Column - II"),((A),S=1mm : N=10,(P),0.05 mm),((B),S=0.5mm : N=10,(Q),0.01mm),((C ),S=0.5 mm : N=20,(R ),0.1 mm),((D),S=1mm : N=100,(S),0.025 mm):}`

Answer

A-R; B-P; C-R; D-Q