Answer:
B. international trade
Step-by-step explanation:
Belgium, Korea and Canada all three are very small economies. In order to take the full advantage of specialisation, these economies has to focus on international trade.
As international trade not only provides for worldwide reach but, also demands for better quality. International standards are to be met. When the economy reaches on the standard where it fulfils the international standards then it reaches the maximum level of specialisation.
As the product is accepted globally and in the international market. After that all other countries recognise it as a specialised country for that specific product.