Final answer:
A 'Published library' is the correct answer for a valid library subscription type in a virtualization or cloud environment. It is a library that has been made available for subscription to allow access across different systems or parts of an organization.
Step-by-step explanation:
Among the subscription types for Content Libraries, a Published library is a valid subscription type. A Published library is one that has been made available (or published) by its owner for other users to subscribe to. This allows users on other systems or within different parts of an organization to access the same content library. The publishing process involves designating a library as published, which then provides you with a subscription URL that you can share with other users.
While 'Local library' and 'Remote library' might sound like plausible options, these terms are not standard for describing subscription types. A 'Shared library,' while a concept in various systems, is not the specific term used either for this context. 'Published library' correctly refers to the type of library in virtualization and cloud environments that can be shared across multiple systems or organizations.