B: By default, storage accounts accept connections from clients on any network. To limit access to selected networks, you must first change the default action.
Azure portal
Navigate to the storage account you want to secure.
Click on the settings menu called Firewalls and virtual networks.
To deny access by default, choose to allow access from 'Selected networks'. To allow traffic from all networks, choose to allow access from 'All networks'.
Click Save to apply your changes.
E: Grant access from a Virtual Network
Storage accounts can be configured to allow access only from specific Azure Virtual Networks.
By enabling a Service Endpoint for Azure Storage within the Virtual Network, traffic is ensured an optimal route to the Azure Storage service. The identities of the virtual network and the subnet are also transmitted with each request.
References: https://docs.microsoft.com/en-us/azure/storage/common/storage-network-security