To answer this question, you need to understand where sub-queries can be nested.
Option A) UPDATE, DELETE, INSERT and SELECT statements - This option is correct because sub-queries can be nested in all of these statements. Sub-queries are used to retrieve data from one table and use it in another table or perform operations on it.
Option B) UPDATE statements only - This option is incorrect. Sub-queries can be nested in UPDATE statements, but they can also be used in other types of statements.
Option C) DELETE statements only - This option is incorrect. Sub-queries can be nested in DELETE statements, but they can also be used in other types of statements.
Option D) INSERT statements only - This option is incorrect. Sub-queries can be nested in INSERT statements, but they can also be used in other types of statements.
The correct answer is A) UPDATE, DELETE, INSERT and SELECT statements. This option is correct because sub-queries can be nested in all of these statements.