Answer: A. The audience will be inspired to fight for other causes.
Step-by-step explanation:
The most likely effect of ending the speech this way is that the audience will be inspired to fight for other causes.
Even though they suffered a setback in their quest to rid the state of nuclear power plants, they didn't prevail, they are motivated as there were people who supported their cause and the experience has laid the foundation for the future and they'll continue marching forward till their voices are heard.