A SQL query becomes slow after data grows. The team must identify whether an inefficient access path or missing index is responsible. Which approach best fits?

1. Bound application connection pools and assess a suitable pooling strategy.
2. Coordinate credential version rollout, client refresh, and retirement of the old credential.
3. Inspect query plans and supported Query Insights diagnostics.
4. Monitor replication lag and route freshness-critical reads to an appropriate consistent source.