A. They are discussed, determined, and documented before the actual feature development Sprints.
B. They are implemented along with functional development of the product.
C. They are added to the Product Backlog and addressed in early Sprints, while always requiring at least some business functionality, no matter how small.
D. They are built by a separate team through the creation of an architectural runway.
Explanation:
Architecture and infrastructure are handled in Scrum by implementing them along with functional development of the product, and by adding them to the Product Backlog and addressing them in early Sprints, while always requiring at least some business functionality, no matter how small, as stated in [2]: “Scrum does not distinguish between developing functionality or architecture. They are developed together, as they are both important and support each other. Architecture is not a separate phase; it is part of the product development. Architecture is added to the Product Backlog as any other feature or functionality.”