The correct answer is: " By showing that the people could overpower the monarch".
The events of the Tennis Court Oath meant the start of the French Revolution in 1789. The members of the Third Estate, had left the Estates General, the assembly organized by the king which gathered the three Estates of the Realm (the three social classes in which the reign was divided) . They considered they had no voice there, as their Estate represented the majority of the population and its decisions could always be overturned by the ones of the other two privileged estates, as each estate had one vote.
The Third Estate founded the National Assembly instead and they took the Tennis Court Oath through which they agreed "not to separate, and to reassemble wherever circumstances require" until a constitution had been drafed. These events preceeded the derrocation and execution of King Louis XVI, the abolition of feudalism and absolute monarchies in France, and subsequently in the whole Europe, and the enactment of the Declaration of the Rights of Man and Citizen, the first declaration of civil rights in the world.
