Which high availability server feature is supported in the BL860 i2 Blade memory?

A.
Memory Mirroring

B.
Memory Online Spare

C.
Memory Lock-Step

D.
Memory Double Chip Spare

Explanation:
http://h18000.www1.hp.com/products/quickspecs/DS_00184/DS_00184.PDF(page 2,
always-on resiliency, first bulleted point)