When you are little, it's not hard to believe you can change the world. I remember my enthusiasm when, at the age of 12, I addressed delegates at the Rio Earth Summit. "I am only a child," I told them ."Yet I know that if all the money spent on war was spent on ending poverty and finding environment answers, what a wonderful place this would be. In school you teach us not to fight with others, to work things out, to respect others, to clean up our mess, not to hurt other creatures, to share, not to be greedy. Then why do you go out and do the thing you tell us not to do ? You grown-ups say you love us, but I challenge you, please, to make your actions reflect your words." I spoke for six minutes and received a standing _ . Some of the delegates even cried. I thought that maybe I had reached some of them, that my speech might actually spur  action. Now, a decade from Rio, after I've sat through many more conferences, I'm not sure what has been accomplished. My confidence in the people in power and in the power of an individual's voice to reach them has been deeply shaken. When I was little, the world was simple. But as a young adult, I'm learning that as we have to make choices -- education, career, lifestyle -- life gets more and more complicated. We are beginning to feel pressure to produce and be successful. We are taught that economic growth is in progress, but aren't taught how to pursue a happy, healthy or sustainable  way of living. And we are learning that what we wanted for the future when we were 12 was ideal and innocent. Today I'm no longer a child, but I'm worried about what kind of environment my children will grow up in. I know change is possible, because I am changing, still figuring out what I think. I am still deciding how to live my life. The challenges are great, but if we accept individual responsibility and make sustainable choices, we will rise to the challenges, and we will become part of the positive tide of change. Which of the following is true according to the passage?
the writer thinks what he thought at the age of 12 is mature. the writer's children will certainly live in an ideal environment. the writer's confidence in the people in power has deeply shaken their voice. the writer's belief does not change when he grows up.