Under which option are index changes not flushed until tables close?

This question is about how MySQL handles changes to indexes. Indexes help speed up searching in your database.

The answer is Option B: -delay-key-write.

Let's break down why:

* -delay-key-write: This option tells MySQL to delay writing changes to indexes until the table is closed. This can improve performance, especially for write-heavy operations.
* Option A & C: These options don't exist in MySQL.
* Option D: While similar in concept to -delay-key-write, it's not the correct option.

Important Note: Delaying index writes can sometimes lead to data loss if the server crashes before the changes are written. So, use it carefully!