Azure Cosmos DB is an example of a platform as a service (PaaS) cloud database provider.
References:
https://docs.microsoft.com/en-us/azure/cosmos-db/database-security

Explanation:
Box 1: Yes
You can use the same account to manage multiple subscriptions. You can create an additional subscription for your account in the Azure portal. You may want an additional subscription to avoid hitting subscription limits, to create separate environments for security, or to isolate data for compliance reasons.
Box 2: No
You cannot merge two subscriptions into a single subscription. However, you can move some Azure resources from one subscription to another. You can also transfer ownership of a subscription and change the billing type for a subscription.
Box 3: Yes
A company can have multiple subscriptions and store resources in the different subscriptions. However, a resource instance can exist in only one subscription.
References:
https://docs.microsoft.com/en-us/azure/cost-management-billing/manage/create-subscription

Explanation

Explanation
References:
https://docs.microsoft.com/en-us/learn/modules/intro-to-azure-government/2-what-is-azure-government