Final answer:
The most powerful tool for a nurse in a database would be a subject database, which primarily indexes articles from specialized scholarly and technical journals related to health.
Step-by-step explanation:
When it comes to databases, the most powerful tool for a nurse would be a subject database. These databases primarily index articles from specialized scholarly and technical journals related to health. They provide in-depth information and research from credible sources that are specific to the nurse's field. Subject databases are particularly useful for nurses who have focused their research topic and need specialized information.