Which statement will execute successfully?

B . True. This statement will execute successfully because it has a single column in the SELECT

statements combined with UNION, and the ORDER BY clause is referencing a valid column in the

result set.

A is incorrect because it uses an ORDER BY clause with two columns, which is not allowed when the

SELECT statements have only one column each. C is incorrect for the same reason as A; it

columns that do not exist in the result set. D is incorrect because it attempts to ORDER BY a second

column, which does not exist in the result of the union.

Reference: Oracle Database SQL Language Reference 12c, Set Operators - The UNION [ALL],

INTERSECT, MINUS Operators