Karen asked, "Where does rain come from?" The best response for her teacher is:

A. "The clouds."
B. "I don't really know, Karen."
C. "How could we find out where rain comes from?"
D. "That's really hard to understand, Karen."

I'll be glad to check your answer.

The best response for Karen's teacher would be C. "How could we find out where rain comes from?" This response encourages critical thinking and problem-solving. It also promotes independent research and learning, allowing Karen to discover the answer herself, which can be a more effective way of learning.