Answer: When queuing is delaying query execution on the warehouse

Option A is correct because multi-cluster warehouses are specifically designed to handle query queuing by automatically scaling out to additional clusters when queries are waiting in queue, ensuring better performance during high concurrency periods. Option B is incorrect as disk spilling relates to insufficient memory for operations, not concurrency management. Option C is incorrect because dynamic vertical scaling refers to scaling up/down warehouse size (S/M/L/XL), not horizontal scaling across clusters. Option D is incorrect as multi-cluster warehouses are most beneficial when there ARE concurrent queries running, not when there are none. The community discussion unanimously supports A with 100% agreement and references to Snowflake documentation confirming that multi-cluster warehouses address query queuing delays.

Author: LeetQuiz Editorial Team