Which two statements are true regarding multiple-row subqueries? (Choose two.)

[answerhappygod]

Which two statements are true regarding multiple-row subqueries? (Choose two.)

A. They can contain group functions.
B. They always contain a subquery within a subquery.
C. They use the < ALL operator to imply less than the maximum.
D. They can be used to retrieve multiple rows from a single table only. E. They should not be used with the NOT IN operator in the main query if NULL is likely to be a part of the result of the subquery.