What is located at a point exactly in between the root and apex (outside diameter) of a gear tooth?

A) addendum
B) dedendum
C) root line
D) pitch line

Addendum

A term often used in mechanical engineering to describe the radial distance between the pitch circle and the outermost point of a gear tooth.

Dedendum

The portion of a gear tooth that lies below the pitch circle, extending down to the root of the tooth.

Pitch Line

An imaginary line in the middle of the gear tooth's profile, where the teeth of two gears effectively mesh without slipping.