B)
2,which
3,which
4,which
5,which
6,that
C)
2,Nick, who is very polite, is an English boy
3,We met in York which/that is a Cty...
4,We saw some Morris dancing which /that is a kind of...
5,We ate fish and chips which /that is a traditional ...
6,It was an awesome trip which /that I will never forget