Correct option is A
The thimble of a micrometer typically has 50 divisions. Each division on the thimble corresponds to a measurement of 0.01 mm (or 0.001 inch), meaning that as the thimble rotates one full turn, the spindle moves by 0.50 mm (or 0.025 inch). The precise graduation on the thimble allows for very accurate measurement, which is essential in various precision engineering applications. This 50-division scale is standard on most micrometers to provide high resolution and accuracy in measurements.
