To print the top element 30, the index 'idx' must be incremented until it reaches 2 (because stack[2] is 30). Option B increments 'idx' while it is less than size - 1, which ensures that idx will be 2 when the loop terminates. Option C starts by incrementing 'idx' and continues to do so while 'idx' is less than size - 1, meaning 'idx' will also be 2 when this loop terminates. Both options will result in printing 'The Top element: 30'.