In loading strategies for data access, which description best captures the trade-off of eager loading?

• A. Always used in every scenario despite cost differences.
• B. Higher upfront data retrieval and memory usage, but fewer subsequent queries.
• C. Lower upfront cost and memory usage, but many additional queries.
• D. No difference in performance.

Answer: (D)

The idea being tested is how eager loading trades upfront data retrieval and memory usage for fewer later queries. With eager loading, related data is fetched as part of the initial query, so you pay more data retrieval and use more memory up front. In return, you reduce the number of subsequent queries you'll need when you actually access that related data, which can improve performance if you’re going to work with many items that each have related data. That’s why the description stating higher upfront data retrieval and memory usage, but fewer subsequent queries, best captures the trade-off. The other descriptions describe scenarios that don’t match eager loading: lower upfront cost with many extra queries (that’s lazy loading), no difference in performance (not true in general), or an insistence it’s always used (not accurate given cost considerations).