What is the purpose of changing ownership of datadir to the ‘mysql’ user?

MySQL is installed on a Linux server and has the following configuration:
[mysqld]
User=mysql
Datadir=/data/mysql
As the ‘root’ user, change the datadir location by executing:
Shell> cp –R /var/lib/mysql/data/mysql/
Shell> chown –R mysql /data/mysql/

What is the purpose of changing ownership of datadir to the ‘mysql’ user?

A.
MySQL cannot be run as the root user.

B.
MySQL requires correct file ownership while remaining secure.

C.
MySQL needs to be run as the root user, but file cannot be owned by it.

D.
The mysqld process requires all permissions within datadir to be the same.

Explanation: