Answer: Append, Complete, Update

Spark Structured Streaming offers three main output modes: **Append**, **Complete**, and **Update**. **Append mode** is the default, where only new rows added to the Result Table since the last trigger are outputted. This mode is ideal for queries where the Result Table's rows do not change. **Complete mode** outputs the entire Result Table after every trigger, suitable for aggregation queries. **Update mode**, introduced in Spark 2.1.1, outputs only the rows that were updated since the last trigger. Therefore, the correct answer is **Append, Complete, Update**.

Author: LeetQuiz Editorial Team