Trade between countries:

**The reasoning** Trade between **countries** means buying and selling goods/services across national borders — like Nigeria exporting crude oil to China or importing rice from Thailand. When trade crosses from one country to another, we call it **international trade** (the prefix "inter-" means "between"). This is the fundamental principle: *domestic* = within one country, *international* = between countries. **Why the wrong options tempt you** **A) Domestic** — This trap works if you're thinking about trade *generally* without focusing on "between countries." Domestic trade happens *within* Nigeria (Lagos selling to Kano), not between nations. **C) Bilateral only** — Sneaky! Bilateral (two countries trading) is *one type* of international trade, but international trade also includes multilateral agreements (many countries). Don't confuse a subset with the whole category. **D) Free** — "Free trade" refers to trade *without tariffs/barriers*, not trade between countries itself. It's describing a policy, not the category. **Quick takeaway** Whenever you see "between countries," automatically think **international** — it's the only term that captures cross-border trade in all its forms.