Let us analyze the behavior of both functions:
For foo(3):
When foo(3) is called, val = 3 > 0 is true.
Inside the loop, it evaluates foo(val--). The postfix decrement val-- evaluates to 3 as the argument to the recursive call, before decrementing val.
Therefore, foo(3) immediately calls foo(3) again.
This causes an infinite sequence of recursive calls with the parameter 3, consuming stack frames continuously until memory runs out.
This results in a stack overflow, leading to abnormal termination (crash).
For bar(3):
When bar(3) is called, it enters while(val > 0) and calls bar(2), which in turn calls bar(1).
Inside bar(1):
The loop condition val > 0 (1>0) is true.
Inside bar(0), val = 0, so the loop while(val > 0) is skipped and bar(0) immediately returns 0.
Control returns to bar(1), where x = x + 0 is executed.
In bar(1), the value of val is still 1 because val - 1 was passed by value and val itself was never modified.
The loop in bar(1) continues with val = 1 > 0 and calls bar(0) repeatedly in an infinite loop without causing a stack overflow (as bar(0) returns immediately each time).
Hence, foo(3) results in abnormal termination, and bar(3) results in an infinite loop.
Thus, option (C) is the correct answer.