People commonly think there is only one Buddha or an Enlightened One, but this is not true because in Buddhism there have been multiple Buddhas. People can only become an Enlightened One once they've reached Nirvana through meditation. The first Buddha was Siddhartha Gautama, option C, a young, rich boy that lived inside a castle and was surrounded by wealth and richness, until he escaped and saw the real world was different, then he started his journey of meditation and self-knowledge.