Answer:
A Ruler scale
Step-by-step explanation:
Graduation refers to the tool that measures the length of any particular object. It contains a mark that points to the exact value on a visible scale. These are the linear scales frequently used and they are both straight as well as curved. The units are usually in inches, millimeters, and centimeters.
The ruler scale is often used to measure the length of an earthworm because it gives the most accurate measurement.