How do you protect the server from modification by non-root users?

We can protect the server from the modification by using the non root users in many ways as follows:

By modifying the PHP settings in the server and by using the configured file as, the configuration of the file is basically depend upon the linux and the PHP script. By disabling the URL from the function of file handling that basically accept the local file as the parameters but it also accept the URL.  It can even now get to outer destinations by utilizing fsockopen or any of the CURL capacities. The safe mode  of PHP is presumably probably the best alternative to secure your server however it very well may be prohibitive. Whenever initiated, experimental mode averts access to records not claimed by Apache and access to condition factors and execution of double projects are likewise debilitated.

Maybe a timeline because it shows what's going on in for a long period of time

The correct answer would be a.