There Are Several Different Types of Spark Plug Thread Inserts

There are several different types of spark plug thread inserts. While having a discussion, Technician A says that when a spark plug uses a sealing washer, the insert is plated with a copper flash. Technician B says that when a spark plug in a cast iron head has a tapered seat, silver-plated inserts are used. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B