a$)$ Consider the EMPI.OYEE Rclation shown below:

$\backslash$table$[[$E$.$No$,$Gender,DName,EName,Grade$],[522,$M$,$Sales,Mathew,A$],[524,$F$,$CustomerCare,Claire,B$]]$

$\backslash$table$[[525,$F$,$Sales,Juliel,B$],[527,$M$,$Production,Albert,C$],[530,$M$,$Production,Edisn,A$],[533,$F$,$Sales,Elizabeth,A$],[535,$F$,$Production,Maric,A$],[537,$M$,$CustomerCare,Einstein,B$]]$

Explain bitmap indexing and how it can be used to answer the following query:

"Find the ENames, who are working in 'Production' department and having A grade."

$($Show how the cuery is answered using bitmap operations and the obtained result$)$