The correct answers are B and D. AWS Cloud design principles encourage making data-driven decisions to determine cloud architectural design (B), as this allows for fact-based improvements over time. Additionally, testing systems at production scale (D) is recommended because it enables you to simulate your live environment at a fraction of the cost of on-premises testing. Option A is incorrect because AWS operates on a pay-as-you-go model, not prepaying for resources. Option C is also incorrect as AWS promotes automation to increase efficiency, not emphasizing manual processes. Option E is incorrect because AWS encourages frequent refinement of operational procedures to adapt to changing requirements and technologies.