Here's why:
* The Sophists were a group of teachers in ancient Greece who specialized in public speaking, argumentation, and persuasive communication. They were known for their skill in rhetoric and their ability to teach others how to use it effectively. They emphasized the importance of using language strategically to win arguments and influence others.
The other options are not directly associated with the invention of rhetoric:
* Epic poetry is a genre of poetry, not a school of thought related to rhetoric.
* Stoicism is a school of philosophy that focuses on virtue and reason, with a different emphasis than rhetoric.
* Pastoral poetry is a genre of poetry that deals with rural life and the idealized simplicity of nature.
While these other areas might have influenced rhetorical theory or practice, the Sophists are specifically credited with the development of rhetoric as a systematic discipline.