History: Which product was an early IBM implementation of the relational model proposed by E. F. Codd?

Introduction / Context:
Understanding the evolution of relational databases helps contextualize modern systems. IBM pioneered relational database prototypes and commercial products following E. F. Codd’s work.

Given Data / Assumptions:

• We focus on IBM’s early relational implementations.
• System R was a seminal IBM research project; DB2 emerged as a commercial product.

Concept / Approach:
IBM’s System R demonstrated relational feasibility. DB2, as a commercial descendant, became IBM’s flagship relational DBMS. Alternatives listed (IDMS, dBase-II, R:base) are not IBM relational flagships; IDMS is network (CODASYL), dBase-II is desktop xBase, R:base is relational but not IBM’s seminal product.

Step-by-Step Solution:

Verification / Alternative check:
Historical overviews consistently identify DB2 as IBM’s enterprise relational DBMS.

Why Other Options Are Wrong:
They either belong to different vendors or different models.

Common Pitfalls:
Confusing early relational research projects with non-IBM commercial offerings.

Final Answer:
DB2