How does Azure Resource Manager differ from the classic deployment model in Azure?

a$.$ Azure Resource Manager is only available in certain regions, while the classic deployment model is available globally

b$.$ Azure Resource Manager only allows you to manage virtual machines, while the classic deployment model allows you to manage all resources

c$.$ Azure Resource Manager allows you to manage resources as a group, while the classic deployment model does not

d$.$ Azure Resource Manager is a newer tool and has more features than the classic deployment model