A Company Currently Has Numerous File Servers Providing Home Directories

A company currently has numerous file servers providing home directories for its employees. Some departments have their own file servers. All corporate users authenticate using Active Directory. The engineering department has their own untrusted AD domain for their file servers. The company is looking for a consolidated solution that requires minimal changes to the environment, and that creates a single namespace for the home directories. What is the recommended solution that will meet this company's requirements?

A) Implement an Isilon cluster and utilize Access Zones.
B) Configure two separate clusters, one for each AD domain.
C) Utilize SmartPools to create two pools to separate the domains.
D) Consolidate onto a single cluster and merge the domains.