Question: What is a key reason why duplicate content might cause an issue with ranking?

1. It creates an inability to use canonical URLs, which dramatically reduces crawl effectiveness,
2. It requires using a 302 redirect, which dilutes PageRank.
3. It triggers an immediate manual action penalty, which delists an entire domain until the duplicate content is removed.
4. It makes it difficult for a search engine to determine the original and authoritative content source.

Answer: The correct answer of the above question is Option D:It makes it difficult for a search engine to determine the original and authoritative content source.