When individuals attempt to use old strategies that do not work when solving new problems, they are focusing on irrelevant information inferring unnecessary constraints experiencing functional fixedness experiencing mental set?

experiencing mental set.

A mental set is a framework that people use for thinking about a particular problem. This is usually influenced both by habit and by desire. Mental sets classify problems into separate classes in order to solve them. However, over-attachment to a mental set, or attachment to the wrong mental set, can decrease a person's problem-solving abilities and creativity.

the answer is:

c. economic output

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