The correct answer is option 'C' - a semicolon (;) is used to terminate the function declaration.

A function declaration is a statement that defines a new function in a program. It specifies the function's name, return type, and parameters, if any. The function declaration is followed by a block of code that defines the function's behavior.

To understand why a semicolon is used to terminate the function declaration, let's break down the components of a function declaration and their purpose:

1. Function name: This is the name given to the function, which will be used to call the function later in the program.

2. Return type: This specifies the type of value that the function will return when it is called. It can be any valid data type, such as int, float, char, void, etc.

3. Parameters: These are optional values that can be passed to the function when it is called. They allow the function to accept input and perform operations on it.

4. Function body: This is a block of code enclosed within curly braces ({}) that defines the behavior of the function. It contains the instructions and statements that will be executed when the function is called.

Now, let's look at the role of the semicolon in the function declaration:

- The semicolon is used to terminate the function declaration statement. It indicates the end of the declaration and separates it from the function body.

- Without the semicolon, the compiler would interpret the function declaration and the function body as a single statement, resulting in a syntax error.

- The semicolon is not used to terminate the function body itself. It is only used to terminate the declaration statement.

- After the function declaration, the function body is written inside curly braces and does not require a semicolon at the end. The function body contains the actual code that will be executed when the function is called.

In summary, the semicolon is used to separate the function declaration from the function body and terminate the declaration statement. It is an essential part of the syntax for defining functions in programming languages.