单项选择题

A.1Cisco2811ISR,1CatalystExpress500G-12TC,2CatalystExpress500-24PC
B.1Cisco2851ISR,CatalystExpress500G-12TC,3catalystExpress500-24PC
C.1Cisco2821ISR,CatalystExpress500G-12TC,2CatalystExpress500-24PC
D.1Cisco2801ISR,1CatalystExpress500-24PC