What is the output of the following C code? void func(int
n) {     if (n == 0) return;     printf("%d ",
n);     func(n-1);     printf("%d ",
n); } func(3);

Tracing the recursion: func(3) prints "3", then calls func(2), which prints "2", then calls func(1), which prints "1", then calls func(0), which immediately returns without printing (base case). Control now unwinds back up the call stack: func(1) resumes after its recursive call and prints "1" again; func(2) resumes and prints "2" again; func(3) resumes and prints "3" again. This produces the sequence: 3 2 1 (going down) followed by 1 2 3 (coming back up) — giving the full output "3 2 1 1 2 3", a classic demonstration of how execution "unwinds" through the call stack after the base case is reached.