Correct Answer: D. Data modeling

Explanation:
Data modeling is a critical phase in the machine learning data preparation process. It focuses on defining the structure, relationships, and constraints of the data to ensure it is well-organized and primed for analysis. This phase includes creating entity-relationship diagrams (ERDs) to visualize data relationships, designing data schemas for logical and physical database structure, and applying data normalization techniques to minimize redundancy and enhance data integrity.

Incorrect Options:

• A. Data collection: This phase is about gathering raw data from various sources and does not involve structuring or defining relationships.
• B. Data pre-processing: This phase involves cleaning and transforming data to improve its quality and usability but does not focus on defining data structures or relationships.
• C. Data integration: This phase focuses on merging data from multiple sources into a single dataset but does not involve defining the schema or relationships of the data.