Which type of query does not retrieve data but instead modifies or deletes database objects?

The correct answer is that a data-definition query is specifically designed to modify or define database objects rather than retrieve data. This type of query includes commands that can create, alter, or drop tables, as well as manage the structure of a database. It does not concern itself with the actual data stored within those objects, which distinguishes it from other types of queries that are focused on data manipulation or retrieval.

In the context of the other options, an update query is mainly used to modify existing records in a database, while a data-manipulation query encompasses various operations, including insertions, updates, deletions, and selections of data. A crosstab query, on the other hand, is specifically designed to summarize data and display it in a matrix format, helping to analyze relationships within the data, but it primarily focuses on data retrieval rather than definition or modification of database structures.