What does the conjunction fallacy suggest about the likelihood of co-occurring events?

The conjunction fallacy highlights a cognitive bias where individuals mistakenly believe that specific conditions are more probable than a single general condition. In the context of the provided question, it suggests that people often perceive co-occurring events (or detailed scenarios) as being more likely than a single event occurring alone.

This fallacy occurs because people tend to use representativeness heuristics, where they judge probabilities based on how closely something matches their mental model or stereotypes, rather than adhering to formal probabilistic rules. For example, if given a description that fits a particular stereotype, individuals might erroneously assume that a specific scenario involving multiple characteristics is more likely than a broader one that includes fewer characteristics, even though the probability dictates otherwise.

Thus, the correct answer captures this cognitive bias by stating that co-occurring instances are treated as if they are more likely than a single instance alone, despite being statistically less likely.