Apologies, I've just re-read the question and it is in fact A. These questions aren't worded that great, you really need to read them very very closely (many times). A. Use an SSO domain across all vCenter Server instances "The platform must provide an administrator with the ability to access virtual infrastructure components across all sites from a single management tool instance" Having a single SSO domain will achieve this. B. Use an SSO domain per region - there are multiple regions, so this will mean multiple SSO domains C. Use an SSO domain per vCenter Server instance - "five physically separate sites" and "Some sites require more than one vCenter Server.". So this will mean MANY SSO domains. D. Use an SSO domain per site - "five physically separate sites". So 5 SSO domains. Not what we want.

vCenter Server instances in Linked Mode provides "The platform must provide an administrator with the ability to access virtual infrastructure components across all sites from a single management tool instance" So a Multisite deployment is correct.

A, for sure ...across ALL SITES from a SINGLE management tool instance...

" administrator with the ability to access virtual infrastructure components across all sites from a single management tool instance"

" administrator with the ability to access virtual infrastructure components across all sites from a single management tool instance"

For single pane of glass they need all vCenters connected with ELM. A is correct.

Can only be A. The platform must provide an administrator with the ability to access virtual infrastructure components across all sites from a single management tool instance

A for sure, the other options it's impossible to have signle view for the whole inventory for other vcenter server.

For everyone who said C - Use an SSO domain per vCenter Server instance How does having an SSO Domain (not joined) give you the ability for a Single Pane Of Glass (SPOG). The answer is A "The platform must provide an administrator with the ability to access virtual infrastructure components across all sites from a single management tool instance."

I THINK IT'S C, AND PUT THE LINKED MODE ON EACH VCENTER

A. Use an SSO domain across all vCenter Server instances The platform must provide an administrator with the ability to access virtual infrastructure components across all sites from a single management tool instance. Single SSO Domain to achieve this.

it is C : https://kb.vmware.com/s/article/2034074

Isn't it A?