Concept:In a federal system, the upper house is created mainly to protect the rights and interests of the component states or regions.
Explanation:A federal state often operates a bicameral legislature.
The lower house represents the people based on population size.
The upper house gives equal representation to each federating unit, no matter its size or population.
This prevents bigger or more populous states from dominating smaller ones.
Therefore, the main purpose of the upper house in most federal systems is to ensure equality among the federating units.
Answer:A. ensure equality of federating units