You need to meet the requirements

A company has an Active Directory Domain Services (AD DS) domain with one physical
domain controller. All client computers run Windows 8.
A client computer hosts a Windows 8 virtual machine (VM) test environment. The VMs are
connected to a private virtual switch that is configured as shown in the Virtual Switch
Manager exhibit. (Click the Exhibit button.)

You have the following requirements:
Configure the test environment to allow VMs to communicate with the host machine.
Minimize impact on the host machine.
You need to meet the requirements.
What should you do?

A.
Create a new virtual switch with a Private Network [CP1] connection type.

B.
Create a new virtual switch with an ExternalNetwork connection type.

C.
Change the VLAN ID of the private virtual switch to Enable Virtual LAN identification.

D.
Create a new virtual switch with an Internal Network connection type.

Explanation:
http://technet.microsoft.com/en-us/library/cc816585(v=ws.10).aspx

Private will not allow communication with the host machine.
External will allow communication with the host machine but also allow access to other
machines on the host machine’s network which is not a requirement.