Where do you define parameter variables?

In the function definition.

Explanation:

Function is the block of statement which is used to perform a special task.

when we define the function, we have call the function as well without calling function is not used.

syntax for calling:

name (argument_1, argument_1, ...);

we put the argument in the calling to function.

syntax for defining:

type name (parameter_1, parameter_2, ...)

{

statement;

}

In the definition, we declare parameter for use the value of arguments pass in the calling.

Therefore, the answer is in the function definition.