Which one of the following statements about the zeolites is false :-

Question

( A ) They are used as cation exchangers.
( B ) Zeolites are aluminosilicates having three dimensional network
( C ) Some of the $SiO^{4-}_{4}$ units are replaced by $AlO^{5-}_{4}$ and $AlO^{9-}_{6}$ ions in zeolites
( D ) They have open structure which enables them to take up small molecules