Explanation:

The correct answer is option 'A' - Tithe.

During the Ancien Régime in France, the Third Estate, which comprised the commoners and peasants, was burdened with various taxes and financial obligations. One of the taxes imposed on the Third Estate was the tithe, which was a mandatory payment made to the church.

**What is a Tithe?**

A tithe is a form of taxation where individuals or households are required to contribute a portion of their income or produce to support the church. In the case of France, the tithe was a tax levied on agricultural output and livestock. It was a significant source of revenue for the Catholic Church, and the Third Estate bore the majority of this burden.

**Role of the Catholic Church in the Ancien Régime**

During the Ancien Régime, the Catholic Church held immense power and influence over French society. It owned vast amounts of land and collected substantial wealth from its various sources of income, including tithes. The clergy, as representatives of the church, did not have to pay taxes themselves, further exacerbating the financial burden on the Third Estate.

**Impact on the Third Estate**

The tithe placed a heavy economic burden on the Third Estate, as it required them to give a significant portion of their agricultural produce and livestock to the church. This tax affected both the rural peasants and urban workers who relied on agriculture for their livelihoods.

The payment of tithes often led to financial hardship for the Third Estate, as they struggled to meet their obligations while also providing for their families and meeting other financial responsibilities. This tax, among others, contributed to the growing discontent and resentment towards the monarchy and the church, eventually leading to the French Revolution.

In conclusion, the tax paid to the church by the Third Estate during the Ancien Régime in France was the tithe. This mandatory payment, collected in the form of agricultural produce and livestock, placed a significant economic burden on the commoners and peasants, further exacerbating their financial hardships.