Final answer:
The Third Estate was justified in forming the National Assembly as they faced unfair voting system and sought to establish a representative body that could govern in the interests of the people.
Step-by-step explanation:
The Third Estate was justified in forming the National Assembly to a great extent.
The Third Estate, which represented the majority of the French population, faced unfair voting system in the Estates General where each estate had one vote. The First and Second Estate, consisting of the clergy and nobility, often rejected proposals by the Third Estate that aimed to address the economic and social issues faced by the commoners.
By forming the National Assembly, the Third Estate sought to establish a representative body that could govern in the interests of the people. This act of political rebellion reinforced the idea of popular sovereignty and paved the way for the French Revolution, which ultimately led to significant political and social reforms.