What best describes the role that the volatile keyword plays in C$?$

Volatile is not actually a valid keyword in either C or $C++$

It indicates to other programmers that the value can change elsewhere, but has no effect on the compiler

It allows for the program to flag a variable as potentially changing outside the current scope, preventing premature compiler optimization

It identifies a section of the code as being non$-$deterministic, meaning that its behavior will depend on the specific compiler used to build that code