Unicameral legislature is a common feature of unitary systems of government, where all legislative powers are vested in a single chamber or house. In a unicameral legislature, there is no separate upper house or senate as found in bicameral systems. Instead, a single body is responsible for passing laws and making decisions on behalf of the people. This system is often used in small countries or those with a homogeneous population, where there is less need for multiple levels of representation. It can also be more efficient and cost-effective than a bicameral system, as there are fewer legislators and less bureaucracy involved. Therefore, the correct answer is unitarism.