Unicameral legislatures are popular in

Analyze the question: A unicameral legislature has only one chamber (house), unlike a bicameral one, which has two (e.g., Nigeria's Senate and House of Representatives). The question asks which system of government commonly uses a single-chamber legislature.

Explain the concept:

• Unitary system: Power is concentrated in one central government. There are no regional governments with independent powers to represent, so a second chamber is usually unnecessary. A single chamber is enough and keeps lawmaking simple and cheap. Examples: Ghana, Sweden (now), Denmark, New Zealand.
• Federal system: Power is shared between central and component units (states). A second chamber is typically needed to give the states equal representation, as in Nigeria (Senate), the USA, and Canada. So federal systems are usually bicameral.
• Confederal system: Sovereign states form a loose union, and the legislature is often a single assembly of delegates from the member states. Some confederations did use one chamber (the Articles of Confederation in the USA, for example), but this is a rarer, more specialized case.
• Rigid system: This describes a constitution that is hard to amend, not a structure of the legislature. It is not relevant here.

Solution:

1. Unicameral means one chamber.
2. The second chamber exists mainly to represent federating units.
3. Unitary states have no such units to represent, so they commonly adopt a single chamber.
4. Federal systems are mostly bicameral, so B is out.
5. Confederal is possible but is not the standard association, and "rigid" does not describe a legislature type.

Correct answer: A. Unitary system

Exam tip: Remember "Federal = Few chambers? No, Federal = Two (bicameral)". Federal needs a second house for the states, while unitary can manage with one. When you see "unicameral," think "unitary" (both start with "uni").