It uses both techniques.

There are many diffferent memory management techniques used in any Operating System, and Linux is no different. The answer is not simple and is beyond the scope of this type of question. I would refer you to any of the Linux kernel books for more in-depth discussion of the techniques that are used.

ask your supervisor

Unix internals refer to the algorithms and techniques used by the resident operating system to manage resources.

Sterile technique is a procedure that includes the medical and the laboratory techniques like with cultures. Sterile technique includes techniques such as flame sterilization and it should be used in hospital operating theatres.