which group I belong to vs to which group I belong?

Question

1. I don't know which group I belong to. 2. I don't know to which group I belong. Which one of the sentences is true? --- Note: An answer was given to this question when it still read "I don't know (to) which group **do** I belong (to)."

Answer 1

According to traditional grammarians, #2 is correct and #1 is incorrect because "good" style dictates that we should not end a sentence with a preposition (i.e. "to"). However, according to my perspective, both versions are acceptable depending on the context. I would use #1 in informal situations and #2 in academic writing.