Final answer:
An effective concluding sentence highlights President Obama's use of repetition in his space exploration speech to underscore the benefits of the space program and leave a lasting impression on the audience.
Step-by-step explanation:
In conclusion, President Obama's strategic use of repetition not only highlighted the significance of the space exploration program but also ensured that his message had a lasting impact on the audience. Through the deliberate use of this rhetorical device, he effectively reinforced the notion of a beneficial return on investment, emphasizing the importance of continued investment in space exploration for the progress of mankind. This speech serves as an exemplary case of how repetition can be utilized in oration to strengthen and unite the overarching message, leaving an indelible impression on its listeners.