The correct answer to this open question is the following.
Although there are no options attached or further references or context, we can say the following.
Regarding the French debt, the costs that seemed justified were the French intervention in the Seven Years War, because France had a great rivalry against England, and France had to send troops to the North American territory and other parts of the European continent.
Another justified cost was the support the government of France offered the Continental Army when it was fighting against the British troops during the Revolutionary War of Independence. At that time, the United Kingdom was the natural enemy of France.
Now, the costs that seemed unjustified were the following. First the construction of luxurious buildings such as the Versailles Palace, in the outskirts of Paris. This was an excessive massive luxurious building in a time where most of the French people were very poor.
The other unjustified cost was the extravagant parties and luxurious lifestyle of the King of France Louis XIV and his wife Maria Antonieta. Fancy parties, fancy clothes, and fancy food, when the Third State in France was dying of hunger.
We then can say that a class conflict started the revolution.
The French Revolution began in 1789. The Storming of the Bastille started the hostilities in Paris, France. French people were tired of the tyranny of the monarch. The class system had produced social inequality and the tax burden on the thirds state (the commoners, the poor people) angered the French.
