Concept:A federal state uses two legislative chambers to balance national unity with regional diversity.Explanation:In a federation, the lower house usually represents the population of the whole country.The upper house is designed to give equal or special representation to the component states or regions.This ensures that localized interests and regional voices are not overshadowed by more populous areas.Hence, bicameralism protects the federal principle of safeguarding state and regional concerns.Answer: B. localized interests receive adequate representation