What was the main reason for increasing customs duties during wartime?

Correct answer: To raise money for government war expenses

The correct answer is C. During wartime, the government needed additional revenue to pay for military operations and other war-related expenses. Increasing customs duties on goods was one way to collect more money. The measure was therefore connected with wartime finance, not with honouring trade, distributing land, or rewarding students, as suggested by the other options.