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Regarding frequent itemset, which of the following are true?
A.
All non-empty subsets of a frequent itemset are frequent.
B.
If itemset A contains a non-frequent subset, then A cannot be frequent.
C.
If all non-empty proper subsets of itemset A are frequent, then A must also be frequent.
D.
The support of itemset A cannot exceed the support of any of its non-empty subsets.