Which of the following scenarios BEST illustrates the concept of rapid elasticity within a cloud-computing environment?
A company's internal web server being reconfigured overnight by IT staff to handle an expected increase in load the following day.
Manually provisioning additional virtual desktops in the cloud prior to a new employee starting their job.
A local email server being manually upgraded with additional storage due to growing number of users.
A cloud service that automatically allocates additional compute resources to a retail website to accommodate increased traffic during holiday sales.