What will be the output of the following program? int f (int x) { static int…

• When i = 0:

  • f(0) is called.

  • y is initialized to 0.

  • y += 0 -> y = 0 + 0 = 0.

  • f(0) returns 0. Thus, a = 0.

• When i = 1:

  • f(1) is called. y retains its previous value of 0.

  • y += 1 -> y = 0 + 1 = 1.

  • f(1) returns 1. Thus, a = 1.

• When i = 2:

  • f(2) is called. y retains its previous value of 1.

  • y += 2 -> y = 1 + 2 = 3.

  • f(2) returns 3. Thus, a = 3.

• When i = 3:

  • f(3) is called. y retains its previous value of 3.

  • y += 3 -> y = 3 + 3 = 6.

  • f(3) returns 6. Thus, a = 6.

• When i = 4:

  • f(4) is called. y retains its previous value of 6.

  • y += 4 -> y = 6 + 4 = 10.

  • f(4) returns 10. Thus, a = 10.

• When i = 5:

  • f(5) is called. y retains its previous value of 10.

  • y += 5 -> y = 10 + 5 = 15.

  • f(5) returns 15. Thus, a = 15.

After this iteration, i becomes 6, the loop condition i < 6 becomes false, and the loop terminates.

Final Print Statement

The program executes printf ("%d", a);, which prints the final value stored in a.

The final value of a is 15.

Therefore, the correct option is 4) 15.