“Plutocracy” means an elite or ruling class whose power derives from their wealth, or to be precise a government formed by the wealthy, hence Option C is the correct answer because it is the most suitable substitute for the given statement.
Option A is incorrect because “aristocracy” means the highest class in a society, typically comprising people of noble birth holding hereditary titles and offices, which is different from plutocracy as that involves the wealthy, hence it is incorrect.
Option B is incorrect because “monarchy” means a form of government with a monarch(king , queen, emperor) at the head, hence it is incorrect.
Option D is incorrect because “oligarchy” means a small group of people having control of a country or organization, which means a government formed by a small number of people which is incorrect.