Geoffrey Is Training to Be a Telemarketing Sales Person

Geoffrey is training to be a telemarketing sales person.Initially he received an incentive bonus for each customer he called on even if the customer did not want his service.Currently,he only receives the incentive bonus for actually getting the customer to try the product.Eventually,he will get paid only when the customer purchases the product.Geoffrey's sales skills are being developed through

A) modeling.
B) shaping.
C) classical conditioning.
D) stimulus discrimination.