The incorrect option is (d) The flow of technology.
The three flows are: trade in goods, migration of labour, and movement of capital for investment — not technology.
Source: The Nineteenth Century (1815–1914), Chapter 3
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The passage clearly states the three types of flows as (1) flow of trade, (2) flow of labour, and (3) flow of capital. Technology is not listed as one of these three flows. Examiners expect you to directly identify the odd one out by recalling this specific list from the textbook.