What process converts a source code written in high-level language into lower-level language?

The process that converts source code written in a high-level language into a lower-level language is known as compiling. During compilation, the high-level code, which is easy for humans to read and write, is transformed into machine code or intermediate code, which is more suitable for a computer to execute. This transformation allows the high-level instructions to be processed by the computer's hardware.

In compiling, the source code goes through several stages including lexical analysis, syntax analysis, semantic analysis, optimization, and code generation. The end product is usually object code or machine code that can be executed directly by the computer's CPU, or further linked with other object files to create an executable program.

While interpreting also involves translating high-level code into lower-level code, it typically does so line-by-line at runtime, rather than producing a standalone executable file like a compiler does. Linking is the process of combining various object files and libraries into a single executable, and debugging is the process of identifying and correcting errors in the program code. Thus, compiling is the most appropriate answer for this question.