The correct answer is: D. all of the mentioned
The deep web is the part of the internet that is not indexed by search engines. This includes websites that require a login, password, or other form of authentication to access, as well as websites that are not linked to from any other website.
Database-generated web pages are pages that are created by a database, rather than being manually created by a web developer. These pages are often used for things like e-commerce websites, where the product catalog is stored in a database and the product pages are generated dynamically based on the user’s search query.
Private or limited access web pages are pages that are only accessible to a specific group of people, such as members of a club or organization. These pages are often protected by a password or other form of authentication.
Pages without links are pages that are not linked to from any other website. This can be because the page is new and has not yet been linked to, or because the page is intentionally hidden from search engines.
All of the above are examples of the deep web.