The third estate refers to the commoners or the majority of the population in France during the Old Regime, which was the social and political system in place before the French Revolution. In this system, society was divided into three estates - the clergy, the nobility, and the third estate. The third estate was made up of commoners, including peasants, artisans, and the bourgeoisie.

The third estate did not enjoy privileges by birth like the clergy and nobility. The clergy, as members of the First Estate, were exempt from paying taxes and enjoyed various privileges, including the collection of tithes from the commoners. The nobility, as members of the Second Estate, also had privileges such as exemption from certain taxes and the ability to hold high-ranking positions in the government and military.

However, the third estate did not have any feudal privileges like the nobility. Feudal privileges were the rights and privileges granted to the nobility based on their status and land ownership. These privileges included the ability to collect taxes, control local courts, and enforce labor obligations on the peasants. The third estate, being mostly peasants and commoners, did not have these privileges.

Therefore, the correct answer is option 'D' - the third estate had no privileges. They were burdened with heavy taxes, feudal obligations, and lacked political representation. They were subject to the whims of the monarchy and had limited opportunities for social and economic mobility.

During the French Revolution, the grievances of the third estate, including their lack of privileges and representation, led to widespread discontent and ultimately, the overthrow of the monarchy. The revolution aimed to abolish the feudal system and establish a more equitable society where all citizens would be equal before the law.

In conclusion, the third estate did not enjoy privileges by birth or feudal privileges. They were the majority of the population and were burdened with heavy taxes and feudal obligations. The lack of privileges and representation for the third estate was one of the main causes of the French Revolution.