Refer to the exhibit. An organization is using an internal application for printing documents that requires a separate registration on the website. The application allows format-free user creation, and users must match these required conditions to comply with the company's user creation policy: minimum length: 3 usernames can only use letters, numbers, dots, and underscores usernames cannot begin with a number
The application administrator has to manually change and track these daily to ensure compliance. An engineer is tasked to implement a script to automate the process according to the company user creation policy. The engineer implemented this piece of code within the application, but users are still able to create format-free usernames.
Which change is needed to apply the restrictions?