HP Z420, Z620 and Z820 workstations are updated to include what family of processors?

A.
Ivy Bridge

B.
NVDIA

C.
Thunderbolt

D.
Xeon

Explanation:
http://www8.hp.com/us/en/hp-news/press-release.html?id=1473065#.UrHp3GQmmZ0(
HP Z workstations get a boost with ivy bridge and thunderbolt)