Which major economic factor created by the First World War most strongly intensified the national movement in India?

Correct answer: Sharp rise in defence expenditure

The First World War sharply increased colonial government expenditure, especially on defence. To finance the war, taxes were raised and additional revenues were sought, while wartime shortages and disrupted supplies contributed to price increases. These pressures affected households and strengthened resentment against colonial rule, helping the national movement. Option A identifies the principal initiating economic factor; foreign trade did not completely stop, taxes were not abolished, and privatisation was not the wartime policy described here.