The correct answer is C) the wars he engaged in were the least successful in the history of France.
The statement about Louis XIV that is an opinion rather than a fact is "the wars he engaged in were the least successful in the history of France."
When you state a fact is because you have arguments, data, facts to prove it. In this case, you need to support what you are saying. When you give your opinion, it is a personal consideration that does not to be supported by facts. An opinion is your personal point of view. In this case, the option "C)" simply states an opinion, that is not supported by an argument.
The other options of the question were A) he insisted that Huguenots convert to Catholicism. B) he strengthened the monarchy by centralizing the government. D) The palace he built at Versailles was part of his plan for controlling the nobles.
