The operators used when a subquery returns multiple rows to be evaluated in comparison to the outer query are . . . . . . . .

This question asks about how MySQL handles subqueries that return multiple rows. Subqueries are queries nested inside other queries.

Let's break down the options:

Option A: IN and NOT IN
* IN checks if a value from the outer query exists within the results of the subquery. * NOT IN checks if a value from the outer query *doesn't* exist within the results of the subquery.

Option B: EXISTS and NOT EXISTS
* EXISTS checks if the subquery returns any rows. It's used when you care if something exists, not the specific value. * NOT EXISTS checks if the subquery returns *no* rows.

Option C: OUTER JOIN and INNER JOIN
* OUTER JOIN and INNER JOIN are used for combining data from two tables. They don't directly handle subqueries returning multiple rows.

Option D: LEFT JOIN and RIGHT JOIN
* LEFT JOIN and RIGHT JOIN are specific types of OUTER JOIN, and also don't directly handle subqueries returning multiple rows.

The answer:
The operators used when a subquery returns multiple rows to be evaluated in comparison to the outer query are IN and NOT IN. They are designed to handle multiple values returned by the subquery.

Remember:
* IN and NOT IN are the most common operators for comparing values in the outer query to multiple results from a subquery.
* EXISTS and NOT EXISTS check for the presence or absence of any rows returned by the subquery.
* JOIN operations combine data from different tables. They're not directly used for this type of subquery comparison.