Answer: The use of warehouse auto scaling, Use of multi-clustered warehouses

The question asks for two Snowflake features that enable virtual warehouses to handle high concurrency workloads. Option B (warehouse auto scaling) allows warehouses to automatically add clusters when query queues form, enabling them to handle more concurrent users/queries. Option D (multi-clustered warehouses) allows multiple clusters to run in parallel, distributing the workload across clusters to handle high concurrency. The community discussion shows 100% consensus on BD, with references to Snowflake documentation confirming that multi-cluster warehouses and auto-scaling are specifically designed for high concurrency scenarios. Option A (scale up warehouses) and C (resize warehouses) involve vertical scaling which increases compute power but doesn't inherently address concurrency. Option E (warehouse indexing) is not a Snowflake feature - Snowflake automatically handles indexing internally.

Author: LeetQuiz Editorial Team