Respuesta :
They can sit together in 12 different configurations:
ABCD
CDAB
CABD
DABC
BACD
CDBA
CBAD
DBAC
ABDC
DCAB
BADC
DCBA
ABCD
CDAB
CABD
DABC
BACD
CDBA
CBAD
DBAC
ABDC
DCAB
BADC
DCBA