Which concept BEST describes the capability for a cloud environment to automatically scale a system or application, based on its current resource demands? 

Answer options:

A. On-demand self-service
B. Resource pooling
C. Measured service
D. Rapid elasticity

D

Rapid elasticity allows a cloud environment to automatically add or remove resources to or from a system or application based on its current demands. Whereas a traditional data center model would require standby hardware and substantial effort to add resources in response to load increases, a cloud environment can easily and rapidly expand to meet resources demands, so long as the application is properly implemented for it.