Select the correct answer from the drop-down menu.

Omar is writing a draft of a research paper about UFOs. Which information should he include to maintain the flow of ideas in his paper?

The shape of celestial bodies often influences reports of unidentified flying objects (UFOs). For example, the rings around Saturn may have influenced our ideas of how otherworldly spacecrafts should appear. Or better yet, strange cloud formations or bright meteor showers could have actually been mistaken for UFOs. Whatever the explanation, UFOs have ____________________ for hundreds of years. Indeed, a sixteenth-century German news notice describes a strange group of cylindrical-shaped objects flying over Nuremberg.

Choices:
- reflected society's beliefs
- been described as circular or cylindrical
- been popular in American culture
- reflected the rings around Saturn