Which system variable when set to 1, makes all temporary tables to get stored on disk rather than in memory?

This question is about temporary tables in MySQL. Temporary tables are like regular tables, but they only exist for the duration of your current database connection.

Normally, temporary tables are stored in memory. This is fast, but it can cause problems if your temporary table gets very large.

There is a system variable in MySQL that lets you control where temporary tables are stored. This variable is called big_tables.

If you set big_tables to 1, then all temporary tables will be stored on disk instead of in memory. This can help to avoid memory issues, but it can also make your queries run slower.

So, the answer to the question is Option C: big_tables.