Answer: Add additional clusters to the virtual warehouse.

The question asks about resolving query concurrency problems, which occur when multiple queries compete for resources simultaneously. Option C (Add additional clusters to the virtual warehouse) is correct because it enables scale-out parallelism, allowing more queries to run concurrently by distributing the workload across multiple compute clusters. This directly addresses concurrency limitations. Option D (Resize to a larger instance size) is incorrect as it provides scale-up (more CPU/memory per cluster) but doesn't inherently improve concurrency - it just makes individual queries faster. Options A and B (search optimization and query acceleration services) are performance optimization features for specific query types but don't directly solve general concurrency issues. The community discussion with 100% consensus on C and explicit rejection of D supports this reasoning.

Author: LeetQuiz Editorial Team