Answer:
Centimeters
Step-by-step explanation:
When you decide on the appropriate length to use when measuring something, you need to consider the size of it. (Unless specified)
So your finger is less than a meter or a kilometer, so we knock those out because the value will be too small. Now you have centimeters and millimeters.
A finger is longer than a centimeter and millimeter, but since the finger is signiifcantly longer than a centimeter, it would be best to use millimeter. You can use millimeter, if what you are measuring is smaller than a centimeter.
