How can we eliminate fake user registration’?

A Drupal corporate website allows editors to self-register with additional administrator approval However, Robots are creating a lot of user accounts and administrators are not able to keep up with the approval process

How can we eliminate fake user registration’?
A . Enable the Drupal core captcha field on the user registration form
B . Hide user login by disabling the login block and/ or move the login page
C . Configure new user accounts to "require email verification when a visitor creates an account."
D . Change who can register accounts to "Administrators only"

View Answer

Answer: D