Concept: Bicameralism means a parliament with two separate chambers.Explanation: Nigeria operates a bicameral legislature made up of the Senate and the House of Representatives.The USA also uses the same structure with its Senate and House of Representatives.The UK, by contrast, has the House of Commons and the House of Lords.China and New Zealand both practise unicameralism, meaning they have only one legislative chamber.Therefore, the Nigerian system closely mirrors the American system.Answer: D. USA