Addendum: 

• It is the radial distance of a tooth from the pitch circle to the top of the tooth.

Dedendum: 

• It is the radial distance of a tooth from the pitch circle to the bottom of the tooth.

Pitch circle: 

• It is an imaginary circle which by pure rolling action, would give the same motion as the actual gear.

Pitch circle diameter: 

• It is the diameter of the pitch circle. 
• The size of the gear is usually specified by the pitch circle diameter.
• It is also called as pitch diameter.

Module: 

• It is the ratio of the pitch circle diameter in millimetres to the number of teeth.
• Module, m = D / T

Hence, the correct option is (B).