When planning for voice deployments with the Cisco Unified Wireless IP Phone 7921G handset in a multifloor building with a WLAN that operates at an 11 MB/s data rate, how many decibels referenced to 1 milliwatt of same-channel separation are recommended between floors?

A.
13 dBm

B.
19 dBm

C.
25 dBm

D.
31 dBm