The number of tables for which DELAYED works is . . . . . . . .

MyISAM, MEMORY, ARCHIVE, BLACKHOLE

Solution (By Examveda Team)

This question is about DELAYED in MySQL, which is a special kind of insert. It's used to delay the actual writing of data to the table until later.

Now, not every table type in MySQL can handle this "delayed writing". The question lists four table types:

* MyISAM: This is a very common MySQL table type.
* MEMORY: These tables are stored in RAM (your computer's fast memory) for very quick access, but they lose their data when the server restarts.
* ARCHIVE: This type is designed for storing large amounts of data that you don't need to change very often.
* BLACKHOLE: These tables are special. They *accept* data, but they *don't actually store it*.

The question asks how many of these table types allow DELAYED inserts.

Here's the breakdown:
* MyISAM supports DELAYED. It lets you queue up inserts and write them to the table later.
* MEMORY doesn't support DELAYED. The data is kept in RAM, so delaying the write doesn't really make sense.
* ARCHIVE doesn't support DELAYED. They are designed for read-only access.
* BLACKHOLE doesn't support DELAYED either. They don't store data, so there's nothing to delay.

Therefore, the answer is Option A: 1. Only MyISAM supports DELAYED inserts.