The is the part of a function definition that shows the function name, return
type, and parameter list.

The function prototype is the part of a function definition that shows the function name, return type, and parameter list.

Explanation:-

In general we write a function definition as:

return_type function_name(parameter list)   //this is the prototype

{

    //function body

}

the correct answer is: a.)it is never appropriate to use acronyms and emoticons in business communication.