Final answer:
The correct option for the prewritten function that is built into a programming language is library function. A library function is a prewritten function that is included in a library or collection of code that can be reused by programmers in their programs.
Step-by-step explanation:
The correct option for the prewritten function that is built into a programming language is library function. A library function is a prewritten function that is included in a library or collection of code that can be reused by programmers in their programs. It provides commonly used functionality and helps to simplify programming tasks. For example, in Python, the 'print' function is a library function that is built-in and can be used to display output on the console.