Answer:
Determination.
Step-by-step explanation:
William Kamkwamba's "The Boy Who Harnessed the Wind" is the author's true story of how he invented the windmill to help his village. William's determination and perseverance helped him "harness" the wind and help bring irrigation to the fields even during the drought.
In the given passage from the text, William recalls how he hung on to the tall tower despite the "sudden gust" of wind. And despite his position of hanging so high up from the ground and his "knees buckled", he stayed on to ensure the blades are moving as expected and that nothing goes wrong.
This shows his determination in making sure that his windmill works.