Answer: Insert-only

The correct answer is C (Insert-only) because Snowflake documentation explicitly states that 'Insert-only' streams are specifically supported for tracking changes in external tables. This is confirmed by the community discussion where multiple users reference the official documentation and the highest upvoted comments (5 upvotes) support option C. While option B (External) might seem intuitive, it is not an actual stream type in Snowflake - the valid stream types are Standard, Append-only, and Insert-only. Insert-only streams are designed specifically for external tables since they can only track new inserts, which aligns with how external tables typically work (read-only access to external data sources).

Author: LeetQuiz Editorial Team