Final answer:
The experimental method would be recommended to determine whether age affects reaction time.
Step-by-step explanation:
The research method I would recommend for Dr. Breslin to determine whether age affects reaction time would be the experimental method.
This method would involve conducting controlled experiments where participants from different age groups are tested on their reaction time.
By comparing the results, Dr. Breslin can determine if there is a significant difference in reaction time among different age groups.