单项选择题
下面有关各种范式之间的包含关系的描述中，正确的是
A．BCNF
4NF
3NF
2NF
1NF
B．4NF
BCNF
3NF
2NF
1NF
C．1NF
2NF
3NF
4NF
BCNF
D．1NF
2NF
3NF
BCNF
4NF
4NF3NF2NF1NFB．4NF
BCNF3NF2NF1NFC．1NF
2NF3NF4NFBCNFD．1NF
2NF3NFBCNF4NF