Students are told that "2-4-6" is one example of a rule; they are asked to determine what the rule is. Many students assume the rule is "three consecutive even numbers" and fail to check whether 1-3-5 is also an example of the rule, or even 1-10-11. What mistake in reasoning have they made?

A) reliance on availability heuristic
B) confirmation bias
C) reliance on representativeness heuristic
D) failure to consider base-rate information

The students have made the mistake of confirmation bias, which is the tendency to search for, interpret, favor, and recall information in a way that confirms one's preexisting beliefs or hypotheses, while giving disproportionately less consideration to alternative possibilities. In this case, they only look for patterns that match their initial assumption (three consecutive even numbers) and fail to test or consider examples that could disprove their hypothesis.