He can use an affirmation that shows the different effects of different therapies at different ages.
We can arrive at this answer because:
Therefore, to show the success in the hypothesis of the experiment, the researcher must show how the relationship between different types of therapy and different ages can have efficient results that would improve the treatment of psychological illnesses.
You didn't show the answer options, which prevents me from providing a specific answer. However, I hope the information above can help you.
More information:
https://brainly.com/question/896413?referrer=searchResults