High in the mountains, and deep in the forest, lives a lake with many plants and animals in and around her. The plants and animals have enough food and clean water to keep them healthy. The wind carries air, and the rain comes down clear and clean. But recently, Lucy Lake and her friends haven't been feeling very well. All the plants and animals get together to talk about the problem. "Why are we sick?" "What can we do?" ask all of them. No one has any answers. Just then two hikers appear. The animals tell them about their problems. "Can you help us?" they ask. "Yes," one hiker says. "I think it's because of acid rain." "Acid rain comes from chemicals  in the air. The pollution comes from factories, cars and trucks." "So, although I don't want to, I help the pollution travel through the air!" says the wind. "And I carry it to the land!" cries the rain. "If you can help us think of some solutions , we will send a message to tell people how to clean up our environment," one hiker says. With the help of the plants and animals, the two hikers make a list of ideas for saving Lucy Lake and her friends. Time passes, and the forest and lake begin to feel a little better. The next time the hikers climb up the mountains to Lucy Lake, they smile at what they find. "We're glad things have started to change," one hiker says. "And we're glad helped us make a difference," says the other. The two hikers are most probably    _   .
scientists teachers doctors reporters