Final answer:
The 'C' in the ACID properties of database transactions stands for Consistency, which pertains to maintaining data integrity by ensuring all transactions bring the database from one valid state to another.
Step-by-step explanation:
The student's question, "Expand on the C of the ACID properties", relates to database transactions and the ACID properties which guarantee that database transactions are processed reliably. The 'C' in ACID stands for Consistency, which ensures that a transaction can only bring the database from one valid state to another, maintaining the integrity of the data. Whenever a transaction is initiated, it must go through four stages to maintain ACID compliance: Atomicity, Consistency, Isolation, and Durability. Therefore, the correct expansion of 'C' is Consistency, and the transaction states it is associated with are from Commit to Consistency (Answer: c) Commit; Consistency), ensuring that all data written to the database must be valid according to all defined rules, including constraints, cascades, triggers, and any combination thereof.