The most appropriate target behavior for a training program designed to teach parents of children with autism to deliver reinforcement effectively would be

to accurately demonstrate the skill in a role play  

Explanation:

Autism is also known as autism spectrum disorder. It is refereed to as the condition which is challenged with the  repetitive behaviors, social skills, speech as well as non verbal communications.  

A target behavior is a behavior which has been chosen for any change in the behavior of the child. It should be a positive behavior or trait.

In the context, the most appropriate target behavior to teach the parents of children having autism in a training period to deliver reinforcement is to accurately demonstrate the skills in a role play. By this the children can learn how to cultivate the skills in themselves and will revive in the behavior.

answer; observing;