Answer: "Neither Jennifer, Thomas, nor I had ever seen the likes of that giant cheeseburger" is a simple sentence.
Step-by-step explanation: A simple sentence is a sentence type that includes a single clause. In other words, a simple sentence presents only one subject and only one verb. Moreover, this sentence type does not contain dependent clauses. Although the sentence provided includes three subjects joined by "neither...nor", it only has one verb ("had seen"). In that way, "Neither Jennifer, Thomas, nor I had ever seen the likes of that giant cheeseburger" is a simple sentence because it expresses a complete thought using only one verb.