Some tools have graduations to show multiple measurements. for example a ruler may have graduations for both millimeters and centimetres. when measuring the length of an earthworm, which graduations would allow for the most accurate measurement

The graduation that would allow for the most accurate measurement would be millimeters. This is because it is more precise and less likely to commit errors in measurement. However, if you want to have a sense of practicality, the centimeter graduations would be more suitable.