Final answer:
MS Access is not considered a common commercial database option because it is suited for smaller scale applications and is limited in handling large databases and multi-user environments.
Step-by-step explanation:
The question asks which of the following is not a common commercial database option: a.) SQL Server, b.) DB2, c.) Postgres, d.) MS Access. While SQL Server, DB2, and Postgres are widely used in commercial settings for their robustness and scalability, MS Access is generally not considered a commercial database solution due to its limitations in handling large-scale databases and multi-user environments. MS Access is more commonly used for smaller scale applications or for individuals and small businesses with modest database needs.