When should you switch from a Relational DB to a Graph DB (Neo4j)?

1. A When the dataset grows beyond ten terabytes and the relational database's internal partitioning logic becomes fundamentally unable to handle horizontal scaling.
2. B When the application requires optimized, high-velocity write throughput for millions of independent, non-relational event logs across several disparate regions.
3. C When the data is highly interconnected and query performance depends on traversing many relationships (e.g., 'Friends of Friends') that would choke standard SQL JOINs.
4. D When strict, multi-row ACID compliance is the primary requirement for a financial transaction system that must maintain absolute consistency at any cost.