How Can AWS Enable a Company to Control Expenses as an Application's

Multiple Choice

How can AWS enable a company to control expenses as an application's usage changes unpredictably?

A) AWS will refund the cost difference if a customer moves to larger servers.
B) The application can be built to scale up or down automatically as resources are needed
C) Spot instances will automatically be used if the price is lower than on-demand instances.
D) Amazon CloudWatch will automatically predict what resources are needed.