The representative heuristic is best described as:

The representative heuristic is correctly identified as estimating based on how well things represent particular prototypes. This cognitive shortcut involves comparing new information or a scenario to existing mental prototypes or stereotypes to make judgments or decisions. When people utilize this heuristic, they tend to assess the probability or frequency of an event based on the degree to which it resembles a typical example or model in their minds.

This process often relies on readily available stereotypes or characteristics to make judgments about a specific instance. For instance, if someone encounters a person who fits the stereotypical image of a scientist—wearing glasses and a lab coat—they might be more likely to believe that this person is indeed a scientist, rather than considering other possibilities. The representative heuristic reflects how patterns and representations can heavily influence decision-making processes, potentially leading to biases.

In contrast, the other options are less accurate in capturing the essence of the representative heuristic. Relying on emotion rather than logic pertains more to how feelings can impact decision-making, while making random guesses does not involve the rational comparison that the representative heuristic entails. Trusting popular opinion relates to social validation rather than the cognitive assessment of prototypes. Thus, the essence of the representative heuristic lies in its focus on similarity and representativeness rather than emotional or arbitrary factors.