A physician is evaluating a patient who presents with symptoms consistent with a very rare genetic disorder. Despite the symptoms, the physician considers that the base rate of the disorder in the general population is extremely low. Therefore, the physician initially leans towards a more common diagnosis that shares some overlapping symptoms, even if the fit isn't perfect. This line of reasoning, while potentially correct, illustrates a cognitive process known as:

Correct answer: D. Representativeness Heuristic

The physician is using the representativeness heuristic, assessing the likelihood of a diagnosis based on how well the patient's symptoms 'represent' or match the typical profile of a disease. While considering the base rate is good, the *initial lean* towards a common diagnosis despite imperfect fit, over a rare but symptomatic one, indicates a reliance on representativeness (how typical the symptoms are for a common disease). If the physician *ignored* the base rate, it would be Base Rate Neglect. Here, they are *using* the base rate to inform their representativeness judgment.