It is A. The traditional guideline limits a wired VLAN to a /24 subnet, which provides enough IP addresses for 253 endpoints. You might have suggested one of three approaches: one VLAN per floor, one VLAN per building, or one VLAN per campus. The one VLAN per floor approach is not recommended because it interferes with roaming and adds complexity. If you did take this approach, the /24 subnets are not large enough for the requirements on every floor. You would need to ask for /23 subnets.
The one VLAN per building approach would work if you considered each building its own RF domain. It provides roaming within a building and, if you are using a single cluster at the data center, between buildings. If you deployed two MCs or clusters, one at each building, though, GRE tunneling would be required to support roaming between buildings.