Which technique do authors use to develop characters? detailing the time period, culture, and place making a statement that is a universal truth using figures of speech and rhetorical devices describing a character by its physical appearance, actions, and dialogue

The correct answer is - describing a character by its physical appearance, actions, and dialogue.

As a writer, you can develop your characters by telling them what to do, giving them particular characteristics (both implicit and explicit), making them talk to other characters, etc. This way, your readers will get the general idea of what your characters are actually like and will form a particular opinion about them.