Your customer has 21 users, each requiring both PC and IP phone connectivity. Which is the correct configuration for this customer?

A.
1 Cisco 2801 ISR, 1 Catalyst Express 500-24PC

B.
1 Cisco 2811 ISR, 1 Catalyst Express 500G-12TC, 2 Catalyst Express 500-24PC

C.
1 Cisco 2821 ISR, 1 Catalyst Express 500G-12TC, 2 Catalyst Express 500-24PC

D.
1 Cisco 2851 ISR, 1 Catalyst Express 500G-12TC, 3 Catalyst Express 500-24PC