Read the excerpt.

Our planet and its people face many complex problems. These problems are more difficult now than at any other time in history. Therefore, it is essential that we have free education for children worldwide because children of today will have to deal with these problems as adults.

Which selection shows evidence that would be appropriate to use when researching this topic?

A. opinions from people who think our planet has many problems
B. pictures of children in classrooms
C. facts about educated children and adults solving problems
D. letters from people who face problems