print(10) -> print(3) -> print(2) -> print(1) -> print(0).
Above mentioned sequence is the function call sequence, as the variable 'x' is declared as static, changes that you make to the variable will persist between function calls. The final value of the variable will be '0'.
Hence the output will be 00000, as we five function calls, x will be printed 5 times.
It's call by value(but the variable we are printing is stored in static memory), and not call by reference.