There are 3 options(Yes, No, Yes by using triggers) and you can check only one of them.

So if it will be Yes by using triggers than also Answer Yes is correct. So Third option can't be correct, because in that case the first option is also correct.

So it reduce options on No and "Yes but without using triggers" (Yes-Yes by using triggers).

And from those 2 options it was easy to choose the correct one.