Transactional SQL typically refers to:

OLTP (Online Transaction Processing) workloads

Frequent inserts, updates, and deletes

Strong ACID properties (Atomicity, Consistency, Isolation, Durability)

The standard database model used for this is the relational database:

Data stored in normalized tables with defined relationships (primary/foreign keys)

SQL used as the primary query language

Designed for transactional reliability and integrity

Why the other options are incorrect:

Snowflake schema (A) and Star schema (D) are data warehouse schema designs, used primarily for analytics (OLAP), not for core transactional workloads.

Hierarchical (B) is an older model largely superseded by relational for general transactional systems and is not the primary model referenced for “transactional SQL.”

Therefore, the best answer is Relational (C).

CompTIA Data+ Reference (concept alignment):

DA0-001 Objectives – Data concepts: relational databases as the core technology for transactional systems.

Study content: difference between relational OLTP systems vs analytic schemas (star/snowflake).