Final answer:
People judge a man smoking and having a heart attack as more probable than just a heart attack due to the conjunction fallacy, influenced by the availability heuristic.
Step-by-step explanation:
The reason most people might judge statement 1 (A man smokes and has a heart attack) as being more probable than statement 2 (A man has a heart attack) is due to what is known as the conjunction fallacy. This fallacy occurs when it is assumed that specific conditions are more probable than a single general one. The correct answer from the provided options would be b) conjunction fallacy. The conjunction fallacy is a type of cognitive error whereby an individual believes that the co-occurrence of two instances is more likely than just one occurring on its own. This type of error often happens because the specific conditions seem to be more representative of typical or known cases, which can be influenced by the availability heuristic. The availability heuristic is a mental shortcut that happens when people judge the frequency or likelihood of events based on how easily examples come to mind.