Automatic tuning continuously monitors the queries executed on a database using its in-built intelligence and enhances the performance. Which of the following Automatic tuning options are used by the Azure SQL database to improve the database performance?

Answer options:

A.Create Index
B.Drop Index
C.FORCE LAST GOOD PLAN
D.All the above

Correct Answer: D 
Create Index, Drop Index and FORCE LAST GOOD PLAN are three automatic tuning options available in Azure SQL Managed Instance and Azure SQL Database. The following table describes these automatic tuning options: 

Option A is incorrect. Create Index, Drop Index, and FORCE LAST GOOD PLAN are three automatic tuning options available in Azure SQL Database.
Option B is incorrect. Not only Drop Index but Create Index and FORCE LAST GOOD PLAN automatic tuning options are also available in Azure SQL Database.
Option C is incorrect. Not only FORCE LAST GOOD PLAN but Create Index and Drop Index automatic tuning options are also available in Azure SQL Database.
Option D is correct. All the given are the automatic tuning options available in Azure SQL Database.
Reference:
To know more about Automatic tuning in the Azure SQL database, please visit the below-given link: 

https://docs.microsoft.com/en-us/azure/azure-sql/database/automatic-tuning-overview#automatic-tuning-for-sql-database