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

Answer: Option B

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!