问题：

[单选]

Your physical environment is configured as shown in the network diagram. The firewall in the diagram is a generic hardware based firewall product.

You are planning to deploy a Windows Server 2008 R2 Hyper-V server to virtualize your current physical environment. You have the following requirements：
- The Web server VM in the perimeter network （also known as DMZ） must be able to communicate with only the SQL Server computer VM through the firewall.
- The SQL Server computer VM must be able to communicate with the Web server VM.
- The client computer VM must be able to communicate with the Web server VM.
- Two dedicated iSCSI networks must available to the SQL Server computer VM.
- A dedicated management interface must be available for the Hyper-V server.
You need to choose the appropriate virtual network configuration.
Which networking solution should you choose？（）

A . Two external networks and four internal networks
B . Three external networks and two private networks
C . One external network and four private networks
D . Two external networks and three private network