Explanation:

- Interpreter: Translates high-level code into machine code line by line. It's used for languages like Python.

- Compiler: Converts entire high-level programs into machine code at once before execution.

- Linker: Combines various object modules and libraries into a single executable program. This is essential for making the program run.

- Loader: Loads and prepares programs for execution. It places them into memory and starts them running.

Correct Answer: Option 3, Linker