Answer:
"The adults have had their chance to fix the world and they have failed." expresses an opinion.
Step-by-step explanation:
An opinion is a statement or belief about something that cannot be proven true or false. It is based on personal thoughts, feelings, and experiences.
In "The Girl Who Silenced the World for Five Minutes", the following excerpt expresses an opinion:
"I'm only a child, yet I know we are all in this together and should act as one single world towards one single goal."
This statement is an opinion because it is a personal belief expressed by the speaker that cannot be proven true or false. It reflects her perspective and values, and it is not based on empirical evidence or facts.