You have a Microsoft 365 tenant. You have 100 IT administrators who are organized into 10 departments. You create the access review shown in the exhibit. (Click theExhibittab.) 
A or A/B? I'm a bit unsure because if the reviewer type is set to "Managers of users" then updating the Manager property on each user should work (so A). But if that's not configured, changing the user properties wouldn't matter. From the context though, looks like A is what they're going for. Anyone see a catch?
My pick: it's A because Azure AD pulls the manager info straight from the Manager property on each user. If you update those attributes, the access reviews will go to the right department heads. Correct me if I'm missing something in the scenario.