Answer: When a column is dropped from the base table

Based on Snowflake documentation and the community discussion consensus (with multiple upvoted comments confirming this), a materialized view becomes suspended when a column is dropped from the base table. This occurs even if the dropped column was not part of the materialized view definition. The other options are incorrect: adding a column (A) does not suspend the materialized view, DML operations (C) are normal operations that materialized views are designed to handle through incremental maintenance, and reclustering (D) is a background operation that doesn't affect materialized view status.

Author: LeetQuiz Editorial Team