Final answer:
If Cathy has copied a quote into her paper but doesn't remember the source, she should not guess, omit the quote, make up a fictional source, or use the quote without attribution. Instead, she should search for the original source using key words or concepts from the quote.
Step-by-step explanation:
If Cathy has copied a quote into her paper but doesn't remember the source, she should not guess, omit the quote, make up a fictional source, or use the quote without attribution. According to academic guidelines, it's important to accurately credit and cite sources to avoid plagiarism and maintain academic integrity. In this case, Cathy should use the information she does remember about the quote (e.g., any key words or concepts) to search for the original source using quotation marks in an online search engine or library database.