What data type combination can you use in a table's multiple key fields?

The correct answer indicates that a table's multiple key fields can utilize a combination of Boolean and string data types. In database design, the choice of data types for key fields is crucial because it affects how data is indexed, searched, and related to other tables.

Boolean data types represent true or false conditions, which are useful for toggling states or indicating binary options within databases. String data types accommodate alphanumeric characters and are versatile for containing names, descriptions, or other textually-based identifiers. Using these two types together allows for the representation of complex keys that can enable more specific queries and relationships.

This combination provides a unique advantage because it allows the definition of key fields that can include both categorical (string) information and logical states (Boolean), thereby creating a more robust key for uniquely identifying records in a table.

In contrast, the other combinations mentioned do not align as well with this functionality. For instance, while integer and dateTime or reference and time types are valid data types, they may not provide the same flexibility or logical differentiation when used in a key context as Boolean and string do. Therefore, the effective utilization of Boolean and string types enriches the capability of managing and relating data in a way that is both efficient and meaningful.