PLS HELP !!

Which sentence from the article shows how William
Kamkwamba solved his village's problem?
A
He used salvaged metal parts, wood scraps
and a used bicycle frame to build a windmill
B
Kamkwamba is now 33 and a graduate of
Dartmouth College in New Hampshire
С
Kamkwamba spoke to three student groups
for more than three hours.
D
Kamkwamba is the star character in a Netflix
film and has been invited to speak at TED
talks on two occasions