Final answer:
The situation is an example of insight, where a solution suddenly comes to mind without conscious reasoning.
Step-by-step explanation:
The situation described in the question is an example of insight. Insight is a problem-solving process where a solution suddenly comes to mind without any conscious, step-by-step reasoning. In Evelyn's case, while she was eating lunch, she had a sudden flash of insight and came up with a possible solution to fix her sewing machine. This is different from trial and error, which involves trying different solutions until the problem is solved, and proactive or retroactive interference, which are types of memory hindrances.