Which statement is true regarding the INTERSECT operator?

Which statement is true regarding the INTERSECT operator?

A.
The names of columns in all SELECT statements must be identical.

B.
It ignores NULL values.

C.
Reversing the order of the intersected tables alters the result.

D.
The number of columns and data types must be identical for all SELECT statements in the query.

Explanation:
http://oraclexpert.com/using-the-set-operators/