Why does the filmmaker decide to make a documentary about Kamkwamba’s story?

Kamkwamba is a hero who improved living conditions in his country.
He is interested in windmills and how they work.
He has learned about Kamkwamba’s story and wants it to reach a wider audience.
He wants to expose the terrible living conditions in Malawi before the windmill was built.

All of the above reasons could potentially contribute to the filmmaker's decision to make a documentary about Kamkwamba's story.