Answer: change data capture (CDC) feed, Kafka

## Explanation In stream processing pipelines, sources are systems or feeds that continuously generate data in real-time. Let's analyze each option: **A. change data capture (CDC) feed** - ✅ **CORRECT** - CDC feeds capture database changes (inserts, updates, deletes) in real-time - They provide a continuous stream of data changes - Commonly used as sources for streaming pipelines **B. Kafka** - ✅ **CORRECT** - Kafka is a distributed streaming platform - It acts as a message broker that can continuously stream data - Widely used as a source for stream processing pipelines **C. Delta Lake** - ❌ **INCORRECT** - Delta Lake is a storage layer, not a streaming source - While it supports streaming reads, it's primarily a data lake storage format - Better classified as a sink or storage destination **D. IoT devices** - ❌ **INCORRECT** - IoT devices generate streaming data, but they are not typically used directly as sources - IoT data usually flows through message brokers (like Kafka) or IoT platforms first - The devices themselves are data producers, not pipeline sources **Key Points:** - Stream processing sources must provide continuous, real-time data - CDC feeds and Kafka are established streaming data sources - Delta Lake is storage, and IoT devices are data producers that need intermediate systems

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