The correct answer is option 'C': Database application and the database.

Explanation:
The DBMS (Database Management System) acts as an interface between the database application and the database in an enterprise-class system. Let's break down the components involved:

1. Database Application:
A database application refers to the software program or set of programs that interact with the database. It is responsible for managing and manipulating the data stored in the database. The database application can be a custom-built application or a commercial software package.

2. Database:
A database is a structured collection of data that is organized and stored in a systematic manner. It can be a relational database, object-oriented database, or any other type of database depending on the requirements of the system. The database stores the actual data that is used by the application.

3. DBMS:
The DBMS is a software system that provides an interface for managing and interacting with the database. It acts as a mediator between the database application and the database. The main functions of a DBMS include data storage, data retrieval, data manipulation, and data security.

Role of DBMS as an interface:
The DBMS plays a crucial role in an enterprise-class system by acting as an interface between the database application and the database. Here's how it facilitates communication between these two components:

1. Data Storage and Retrieval:
The DBMS provides mechanisms for storing and retrieving data from the database. It manages the physical storage of data on disk and provides efficient algorithms for accessing the data based on user queries from the application.

2. Data Manipulation:
The DBMS allows the application to perform various operations on the data stored in the database. This includes inserting new data, updating existing data, deleting data, and querying the database to retrieve specific information. The DBMS ensures data integrity and consistency during these operations.

3. Data Security:
The DBMS enforces security measures to protect the data in the database. It provides mechanisms for user authentication, access control, and data encryption. It ensures that only authorized users can access and modify the data, thereby maintaining the confidentiality and integrity of the information.

In conclusion, the DBMS acts as a vital interface between the database application and the database in an enterprise-class system. It enables efficient storage, retrieval, manipulation, and security of data, ensuring seamless communication between the application and the underlying database.