What Should an Architect Use as a Guideline to Determine

What should an architect use as a guideline to determine when to minimize VLANs in a wireless design?

A) the WLAN or SSID, with a different VLAN for each SSID
B) the coverage area, with a different VLAN for every 4000 square feet (372 square meters)
C) the number of devices, with a different VLAN for each 250 devices
D) the employee roles, with a different VLAN for each role or department