Which of the questions Ha’s brothers ask seem like reasonable questions?

In context, their questions are all reasonable... they know nothing about their father's whereabouts, and they are grasping as straws. I think they are well aware thet their father wouldn't just run off and start a new family or join a monastery... their questions speak to their confusion.

Brother Quang asks what if
Father escaped to Cambodia
and is building an army
to go back and change history?
Vu Lee asks what if
Father escaped to France
but can’t remember his own history,
so he builds a new family and is happy?
Brother Khôi asks what if
Father escaped to Tibet
after shaving his head
and joining a monastery?