The correct answer is B. Add more clusters to the warehouse.

Queued queries on a multi-cluster warehouse usually indicate a concurrency problem. Multiple analysts are submitting queries at the same time, and the warehouse does not have enough active cluster capacity to process them concurrently.

Why B is correct:

Adding more clusters to a multi-cluster warehouse increases concurrency capacity. In Auto-scale mode, Snowflake can start additional clusters as needed, up to the configured maximum, to reduce queuing.

Why the other options are incorrect:

A . Scheduling or limiting reports may reduce concurrency, but it adds operational overhead and does not use Snowflake's built-in multi-cluster scaling capability.

C . Increasing warehouse size can make individual queries faster, but it does not directly improve concurrency as effectively as adding clusters.

D . A Snowpark-optimized warehouse is intended for memory-intensive Snowpark workloads, not for reducing query queues from many concurrent BI/ad hoc users.

Official Snowflake documentation reference:

Snowflake documentation explains that multi-cluster warehouses are designed to handle concurrency by automatically scaling out with additional clusters.