(C) Removal of restrictions on trade
Liberalisation means removing barriers such as taxes and quotas on trade and investment to allow free movement of goods and services between countries.
Source: Summing Up / WTO section, Chapter 4
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The passage explicitly states: "liberalisation of trade and investment has facilitated globalisation by removing barriers to trade and investment." Options A and D describe protectionism (the opposite), and B (banning foreign companies) is an extreme restriction. The examiner expects you to recall that liberalisation = removal of trade/investment restrictions.