Final answer:
The Third Estate formed the National Assembly due to the unfair voting system and taxation policies in France.
Step-by-step explanation:
The Third Estate formed the National Assembly in response to the unfair voting system and taxation policies in France. The First and Second Estates, which consisted of the nobility and the clergy, held significant privileges and enjoyed tax exemptions, while the commoners in the Third Estate, who made up the majority of the population, were heavily taxed. The Third Estate refused to participate in the Estates General until the voting system was reformed. When their demands were not met, they declared themselves the National Assembly, asserting their right to govern in the interests of the people.