HOTSPOT
Your network contains an Active Directory domain named contoso.com.
You have a failover cluster named Cluster1 that contains two nodes named Server1 and
Server2. Both servers run Windows Server 2012 R2 and have the Hyper-V server role
installed.
You plan to create two virtual machines that will run an application named App1. App1 will
store data on a virtual hard drive named App1data.vhdx. App1data.vhdx will be shared by
both virtual machines.
The network contains the following shared folders:
An SMB file share named Share1 that is hosted on a Scale-Out File Server.
An SMB file share named Share2 that is hosted on a standalone file server.
An NFS share named Share3 that is hosted on a standalone file server.
You need to ensure that both virtual machines can use App1data.vhdx simultaneously.
What should you do?
To answer, select the appropriate configurations in the answer area.
Answer: 
Location of App1data.vhdx: Share1
App1data.vhdx disk type: Dynamically Expanding
differencing disk
You can associate more than one differencing disk to one parent, which means that virtual machines can share one parent disk but have their own differencing disk
https://technet.microsoft.com/en-us/library/cc720381(v=ws.10).aspx
Stand alone file server sounds more logical to me
Folder Redirection, Offline Files, Roaming User Profiles, or Home Directories generate a large number of writes that must be immediately written to disk (without buffering) when using continuously available file shares, reducing performance as compared to general purpose file share
https://technet.microsoft.com/en-us/library/hh831349.aspx
Correct.
Explanation:
* Simultaneous access to vhd can only be done by scale-out file server
* Create your VHDX data files to be shared as fixed-size or dynamically expanding, on the disk where you manually attached the Shared VHDX filter. Old VHD files are not allowed. Differencing disks are not allowed.
Windows Server 2012 R2 Storage: Step-by-step with Storage Spaces, SMB Scale-Out and Shared VHDX (Virtual)
Very helpful.
Thanks.