to which I belong?

[yamyam]

Hello, teachers.

I've found the following:

1. This is the group which I belong to.

The reference book says "You can't move 'to' in front of the relative pronoun 'which' in this case."

Is that so? Is the following #2 wrong? If so, would you tell me why?

2. This is the group to which I belong.

By the way, #3 in the following is correct, right?

3. This is the group I belong to.


Thank you very much in advance for your help.

yam.

 

[SoothingDave]

#2 is fine, but #3 is most natural.

 

[Tdol]

#2 would work in formal contexts, but in informal ones it would sound odd.