The correct answer is B. The beginning of the First World War caused a radical change for the cultural activity and for the life of Debussy due to the lack of commissions aggravated his economic problems. Despite these circumstances, he never stopped writing.
Debussy was inspired by the nationalism during the beginning of the First World War to write his last project. It was a cycle of six sonatas in which was the «Sonata for flute, viola, and harp», one of his most beautiful pieces.