Final answer:
The AND operator is used in a query by example (QBE) form when all specified conditions need to be met for a record to be selected in the query results.
Step-by-step explanation:
The operator used when all the conditions in a query by example (QBE) form are required to be met is the AND operator. In QBE, the AND operator ensures that each row in the result meets all the criteria specified across multiple fields; every condition you input must be true for a record to be included in the results. In contrast, the OR operator is used when you want to retrieve records that meet at least one of a series of conditions, and the NOT operator is used to exclude records that meet the following condition.