Which solution enhances the ability of a cloud infrastructure to exhibit the essential cloud characteristics as defined by NIST?
A. implementation of XML-RPC-based APIs to allow consumers to provide broad access cloud resources from supported end clients
B. implementation of site-to-site VPN connections to provide access to cloud resources across a broad range of consumer internal networks
C. implementation of SSL VPN connections to allow consumers broad access to cloud resources with VPN client software
D. implementation of REST-based APIs to allow consumers to provide broad access to cloud resources from supported end clients
