Answer: Increase the number of streaming units (SUs).

The Backlogged Input Events metric in Azure Stream Analytics indicates that the job is receiving more events than it can process, leading to a growing queue of unprocessed events. This backlog occurs when the job's processing capacity is insufficient for the incoming event rate. **Why Option B is correct:** - Increasing the number of Streaming Units (SUs) directly scales the processing capacity of the Stream Analytics job - Each SU provides approximately 1 MB/second of processing throughput - Scaling up SUs allows the job to process events faster, reducing and eventually eliminating the backlog - This is the primary scaling mechanism for handling increased event volumes in Stream Analytics **Why other options are not suitable:** - **Option A (Change compatibility level):** Compatibility level affects query language features and behavior, not processing capacity or throughput - **Option C (Use $default consumer group):** Consumer group configuration affects how events are read from Event Hubs, but doesn't address insufficient processing capacity - **Option D (Create additional output stream):** Adding outputs doesn't increase processing capacity for input events; it only creates additional destinations for processed data The most effective solution for a consistently growing backlog is to increase the job's processing capacity by scaling up the Streaming Units.

Author: LeetQuiz Editorial Team