The grant table scope columns that is case insensitive is . . . . . . . .

The grant table scope column that is case insensitive in MySQL is User.
In MySQL, the usernames stored in the grant tables are case insensitive, meaning that MySQL does not distinguish between usernames based on case.
Option A, Host, is incorrect because the Host column in the grant tables is case sensitive, as it specifies the host from which a user can connect to the MySQL server.
Option C, Password, is incorrect because the Password column in the grant tables is case sensitive, as it stores the encrypted passwords for users.
Option D, Db, is incorrect because the Db column in the grant tables is case sensitive, as it specifies the databases to which a user has access privileges.