C Preprocessor - General Questions

What will be the output of the program?

#include <stdio.h>
#define LEVEL 2
int main(void) {
#if LEVEL > 1
    printf("high\n");
#else
    printf("low\n");
#endif
    return 0;
}

What will be the output of the program?

#include <stdio.h>
#define X 10
#undef X
#define X 20
int main(void) {
    printf("%d\n", X);
    return 0;
}

What will be the output of the program?

#include <stdio.h>
int main(void) {
    printf("%d\n", __LINE__);
    return 0;
}

Which of these is NOT a preprocessor directive?

What will be the output of the program?

#include <stdio.h>
#define PI 3.14
int main(void) {
    printf("%.2f\n", PI * 2);
    return 0;
}