Answer: Type 2

## Explanation In data warehousing, Slowly Changing Dimensions (SCDs) are strategies for managing changes to dimension data over time. The question specifically describes a scenario where: - Dimension attribute values need to be tracked over time - Full history must be preserved - New rows are added when data changes This perfectly matches **Type 2 SCD** characteristics: ### Why Type 2 (Option C) is Correct: - **Preserves Complete History**: Type 2 SCD maintains a full historical record by adding new rows for each change, rather than overwriting existing data - **Row-Based Tracking**: Each version of a dimension member gets its own row with effective date ranges (start_date and end_date columns) - **Historical Analysis**: Enables time-based analysis and reporting by maintaining all historical states of dimension attributes - **Common Practice**: This is the most widely used SCD type for tracking historical changes in data warehousing ### Why Other Options Are Not Suitable: **Type 0 (Option A)**: Retains original values and never changes - does not track any historical changes **Type 1 (Option B)**: Overwrites old data with new values - loses historical information entirely **Type 3 (Option D)**: Adds new columns for previous values but only tracks limited history (typically just the previous value) - does not preserve complete history through new rows Type 2 SCD is the optimal choice when business requirements demand maintaining a complete historical record of dimension attribute changes, which aligns precisely with the scenario described in the question.

Author: LeetQuiz Editorial Team