Dr Roth Is Working in a Clinic with Children with Developmental

Dr. Roth is working in a clinic with children with developmental delays and decides to implement a new program to encourage more positive behaviours. Whenever children engage in specific behaviours (such as saying, "Thank you," taking turns with a friend, and co-operating with another child on a project) , they are rewarded with stickers that can later be turned in for various prizes that they enjoy. Dr. Roth is using which of the following therapeutic techniques?

A) a token economy
B) negative reinforcement
C) exposure therapy
D) higher order classical conditioning