The superuser account of the grant tables in the mysql database is called . . . . . . . .

This question is about the special user account in MySQL that has the highest level of permissions. It's like the "admin" account in other systems.

Let's break down the options:
Option A: super - This doesn't sound like a typical database user name.
Option B: prime - This doesn't sound like a typical database user name either.
Option C: root - This is the common name for the superuser in MySQL.
Option D: leaf - This isn't related to database administration.

Therefore, the correct answer is Option C: root.
The "root" account in MySQL has full access to all databases and tables. It can create, delete, modify, and manage everything. It's very powerful, so use it with caution!