Which two statements about sub queries are true?

Which two statements about sub queries are true? (Choose two.)

A.
A sub query should retrieve only one row.

B.
A sub query can retrieve zero or more rows.

C.
A sub query can be used only in SQL query statements.

D.
Sub queries CANNOT be nested by more than two levels.

E.
A sub query CANNOT be used in an SQL query statement that uses group functions.

F.
When a sub query is used with an inequality comparison operator in the outer SQL statement,
the column list in the SELECT clause of the sub query should contain only one column.

Explanation:
sub query can retrieve zero or more rows, sub query is used with an
inequality comparison operator in the outer SQL statement, and the column list in the SELECT
clause of the sub query should contain only one column.
Incorrect answer:
Asub query can retrieve zero or more rows
Csub query is not SQL query statement
Dsub query can be nested
Egroup function can be use with sub query