The correct answer is D. Database Administrator.
A Data Engineer is responsible for building and maintaining the data infrastructure that Data Scientists and Data Analysts use to do their work. A Data Analyst is responsible for cleaning, transforming, and analyzing data to find insights. A Data Scientist is responsible for developing and applying machine learning models to solve problems. A Database Administrator is responsible for the performance, security, and availability of databases.
While Database Administrators are important for the overall success of a Data Science team, they are not a key role in the sense that they do not directly contribute to the development of data science products or services.