What is the longest extant part of the Satyricon?

The longest extant part of the Satyricon is indeed the cena Trimalchionsis, which is the famous banquet scene hosted by the wealthy freedman Trimalchio. This segment is particularly notable for its vivid depiction of Roman society, the excesses of wealth, and satirical commentary on social status. The cena serves as a central episode in Petronius's narrative, showcasing the absurdities of Roman social life and the hubris of Trimalchio himself.

This section stands out not only for its length but also for its rich detail and comedic elements, capturing the atmosphere of a lavish feast complete with extravagant food, entertainment, and the interactions among various guests from different social classes. Its significance in the broader context of the work speaks to the themes of decadence and morality in imperial Rome.

The other choices, while interesting and relevant to the overall narrative of the Satyricon, do not match the extensive length and detailed elaboration found in the cena Trimalchionsis. They either represent shorter fragments or thematic explorations that do not have the same depth or prominence in the text.