Answer: Fixed ratio schedule
Explanation:
According to the question, chrissie behavior support the fixed ratio schedule as she text the message on every 40 sec and receive the free soda bottle. In the fixed ratio schedule is the type of schedule of the reinforced in which the response is given after some specific number of the response.
The fixed ratio schedule is a specific number and the fixed amount of the scheduled time. The fixed ratio is the constant that should be deliver with the constant number of the response that deliver correctly.
