What will be the output of the following C code?

#include<stdio.h>
#define hello 10
void main()
{
    printf("%d",hello);
    #undef hello
    printf("%d",hello);
}

What is the purpose of the C preprocessor in C programming?

A. Compile C code

B. Optimize code

C. Preprocess code before compilation

D. Execute code

Which directive is used to include the contents of another file in a C program using the C preprocessor?

A. #define

B. #include

C. #ifdef

D. #pragma

What is the purpose of the #define directive in C preprocessing?

A. To include a header file

B. To define a macro

C. To declare a constant

D. To declare a variable

In C, which directive is used to conditionally include code based on preprocessor macros?

A. #ifdef

B. #ifndef

C. #if

D. #else