Explanation:

Answer: (d). Both a and b

A Database Management System (DBMS) is defined as the software system that allows users to define, create, maintain and control access to the database. DBMS makes it possible for end users to create, read, update and delete data in database. It is a layer between programs and data. Main advantages of DBMS are

• Reducing Data Redundancy
• Sharing of Data
• Data Integrity
• Data Security
• Data Consistency
• Backup and Recovery