X = 0;
y = 0;
Execution Sequences:
1. A -> B -> C ->D, Thus, o/p X=6, Y=4
2. A -> C -> B -> D, Thus, o/p X=6, Y=5
3. C -> D -> A -> B, Thus, o/p X=1, Y=5
4. A -> C -> D -> B, Thus o/p X=6, Y=10
As we can see that outputs 1,2 and 3 are possible but not 4th.
123 is correct option.