Introduction:
In JavaScript, functions are blocks of reusable code that perform specific tasks. They can accept input values, called parameters, which allow us to pass data into the function for its operation. The purpose of using parameters in JavaScript functions is to make the function more flexible and versatile. They enable us to customize the behavior of the function by passing different values as arguments.

Explanation:
The correct answer is option 'C': Parameters allow us to pass values into a function for its operation. Let's explore this answer in detail:

1. Passing Values: Parameters in JavaScript functions act as placeholders for values that are passed when the function is called. They allow us to provide input to the function and modify its behavior based on those values.

2. Customization: By using parameters, we can make our functions more versatile and reusable. We can pass different values as arguments each time we call the function, which allows us to perform similar operations on different data.

3. Function Signature: Parameters are defined in the function signature, which specifies the name of the function, followed by a set of parentheses containing the parameter names. For example, `functionName(parameter1, parameter2)`.

4. Function Invocation: When a function is called, the values passed as arguments are assigned to the corresponding parameters within the function. These parameters can then be used within the function body to perform operations.

5. Multiple Parameters: JavaScript functions can have multiple parameters separated by commas. This allows us to pass multiple values and access them within the function.

6. Default Values: In JavaScript, we can also assign default values to parameters. If no value is passed for a parameter, the default value is used instead. This provides flexibility and allows the function to work even if certain parameters are not provided.

7. Scope: Parameters create local variables within the function, which means they have their own scope. This allows us to use the parameter values within the function without affecting variables with the same name outside the function.

Conclusion:
In JavaScript, using parameters in functions is essential for accepting input values and customizing the behavior of the function. They allow us to pass values into a function for its operation, making the function more versatile and reusable. Parameters define the function signature, provide local variables within the function, and enable us to perform operations on different data by passing different values as arguments.