Virtual warehouses in Snowflake are part of the compute layer, which is responsible for executing queries and processing data. The Snowflake architecture consists of three main layers: storage layer (where data is stored), compute layer (virtual warehouses that process queries), and cloud services layer (orchestration, security, metadata management). The community discussion shows 100% consensus on option A with multiple users confirming 'Compute layer' as the correct answer, supported by upvotes and clear reasoning that virtual warehouses provide the computational resources for query execution.