Final answer:
A transaction in a database is a work unit comprising SQL statements with a unique ID and defined start and end points. It is essential for ensuring data integrity, differentiating database management systems from file systems.
Step-by-step explanation:
The logical units of work that contain one or more SQL statements and/or other programming constructs, which have a beginning and an end, are known as transactions. A transaction is identified by a unique transaction ID, and it is an essential concept in database management systems. This is because the use of transactions allows a management system to differ from file systems by ensuring data integrity and consistency. Therefore, the correct answer to the student's question is C. Transactions.