The correct answer is C

Correct answer is C StoreFront server group deployments are only supported where links between servers in a server group have latency of less than 40 ms (with subscriptions disabled) or less than 3 ms (with subscriptions enabled). Ideally, all servers in a server group should reside in the same location (data center, availability zone), but server groups can span locations within the same region provided that links between servers in the group meet these latency criteria. Examples include server groups spanning availability zones within a cloud region, or between metropolitan area data centers. Note that latency between zones varies by cloud provider. Citrix do not recommend spanning locations as a disaster recovery configuration, but it may be suitable for high availability. StoreFront server groups containing mixtures of operating system versions, or mixtures of operating system languages or locale configurations, are not supported.

B is correct. StoreFront server groups containing mixtures of operating system versions and locales are not supported. StoreFront server groups can contain a maximum of six servers. However, from a capacity perspective based on simulations, there is no advantage of server groups containing more than three servers. Ideally, all servers in a server group should reside in the same location (data center, availability zone), but server groups can span locations within the same region provided that links between servers in the group meet minimum latency criteria https://docs.citrix.com/en-us/storefront/1912-ltsr/system-requirements.html