The two correct answers that Aristotle believed were essential to all plays are:
- Plot
- Tension (though traditionally Aristotle discussed "thought" or "dianoia" which relates closely to tension in a play)
Among the options given, "plot" is definitely one of the primary elements. "Tension" could be considered as an important dramatic element in the broader sense of conflict and engagement in the narrative, but is not explicitly one of Aristotle's formal categories. However, achieving tension is a common outcome of effective plot development. "Audience," "soliloquy," and "monologue" are not listed as essential elements in Aristotle's analysis.