In the WLAN Planner tool, under what circumstances will it not prompt whether to enter roaming mode when walking on a 3D floor?

In the WLAN Planner tool, under what circumstances will it not prompt whether to enter roaming mode when walking on a 3D floor?
A . The number of AP is greater than 50 or equal to 0
B . The number of APs is greater than 100 or equal to 0
C . When the signal strength on the floor is too low
D . When there are insulating obstacles

Answer: D