Doubt in database transaction question

Question

can someone please explain me what this https://gateoverflow.in/3828/gate2005-it-66

question trying to ask ?

Answer 1

They want to ask flow of a transaction....

 

comparing with C program

#include<stdio.h>
int main()
{
      int a;
      scanf("%d",&a);
      f1(a);
}

void f1( int k )
{
      if( k == k1 )  // Assume k1 and k2 are constants
             f2();
      else if( k == k2 )
             f3();
      else
             f4();
}

just like, main() ----> f1() ----> f2() or f3() or f4()

But who will call main() ..... in our case OS right ?

Actually, Option C is not exact right answer... it is better among them