HOTSPOT
Your company has four offices. The offices are located in Montreal, Seattle, New York, and Miami.
Users access all of the web-based resources by using web proxy servers. The IP addresses of the web
proxies at each office are configured as shown in the following table.
The connections to the web proxies are balanced by using round-robin DNS.
The company plans to deploy a new application. The new application has a farm of front-end web
servers that connect to a back-end application server. When a session to a web server is established,
the web server stores data until the session closes. Once the session closes, the data is sent to the
application server.
You need to ensure that the incoming sessions to the web server farm are distributed among the
web servers. The solution must ensure that if a web server fails, the users are NOT directed to the
failed server.
How should you configure the port rule? To answer, select the appropriate options in the answer
area.
Answer: 
Multiple host and Network
Multiple and None surely? Network would mean that any machines coming from a given subnet will be directed to the same hosts – if that host fails, they would still be trying to connect to it. None means they have no affinity with any host and would then just hit one of the available ones.
affinity none is wrong since the host stores session data:
– When a session to a web server is established,the web server stores data until the session closes.
https://technet.microsoft.com/en-us/library/cc771709.aspx
also, the question states users connect through proxies
Class C is used when Internet clients connect through proxy servers with different IP addresses within the same Class C IP address range
Source: https://technet.microsoft.com/nl-nl/library/cc759039(v=ws.10).aspx
Answer is correct and agree with LB explanation
Multiple hosts and network.
See my explanation from http://www.aiotestking.com/microsoft/how-should-you-configure-the-port-rule/#comment-1256099
Source: https://technet.microsoft.com/en-us/library/cc771709(v=ws.11).aspx