How many of the following do not return rows?

SELECT, SHOW, DESCRIBE

This question asks us to figure out how many of the given MySQL commands (SELECT, SHOW, and DESCRIBE) won't produce any results. Think of it like asking which commands are "empty" when used.
Let's break it down:
* SELECT: This command is used to retrieve data from tables. It will always return rows if data exists.
* SHOW: This command is used to display information about the database, like tables, databases, etc. It usually returns rows.
* DESCRIBE: This command is used to show the structure of a table (its columns and their data types). It always returns rows.
Since all three commands usually return rows, the answer is Option D: 3. None of them typically return an empty set of results.