The HP Z1 workstation is the only workstations and offers which of these processors?

A.
NVIDIA Quadro processors

B.
AMD Core ULT series processors

C.
Intel C602 processors

D.
quad core Intel Xoon processors

Explanation:
http://h10010.www1.hp.com/wwpc/pscmisc/vac/us/product_pdfs/Z1_Datasheet.pdf
(second para, page 1)