While Validating the Value (VTV) with a Large Educational Customer

While validating the value (VTV) with a large educational customer, they have decided they would like to add a Disaster Recovery (DR) site to their existing Isilon environment. The existing cluster contains six X-Series nodes. They plan to have all workflows replicated to the DR site and both clusters will have identical shares, exports, and user authentication. The customer would like to test DR failover every six months by running their production environment from the DR site. What would you recommend for the DR solution?

A) SyncIQ and identical cluster at the DR site
B) SmartConnect and NL-Series nodes at the primary site
C) SyncIQ and NL-Series nodes at the DR site
D) Equal number of S-Series nodes at the primary site