What are the minimum system requirements to install Cisco Unity Connection?

A.
1-GHz processor, 1-GB RAM, 80-GB hard disk

B.
2-GHz processor, 2-GB RAM, 80-GB hard disk

C.
2-GHz processor, 2-GB RAM, 160-GB hard disk

D.
3-GHz processor, 4-GB RAM, 160-GB hard disk