For the question about the INTERSECT operator in SQL:
A . It processes NULLS in the selected columns: The INTERSECT operator compares two SELECT statements and returns rows that exist in both queries. It considers NULLs during this process, and NULLs in corresponding columns must match for rows to be considered equal. This means if both selected columns in the intersecting queries have NULLs, those rows will be included in the output.
Incorrect options:
B: INTERSECT has higher precedence than UNION and UNION ALL, not lower.
C: It does not ignore NULLs; rather, it processes them, as explained.
D: Multiple INTERSECT operators are indeed possible in the same SQL statement, allowing for complex compound queries.