However you cut it it’s one parent or two. One parent is always better than two.
I thought you were joking but from the pattern of your other comments I see you actually beleive this. How about a third option, when someone threatens to kill your parents, you kill them instead of making a deal with them on who they murder? Did you even think about that possibility?
Seems like you choose to put yourself in a trolley problem, rather than life actually putting you in one.