An organization has an Office 365 tenant and uses an Enterprise E3 subscription. You enable licenses for 1,000 users.
You must implement a file sync service for users that meets the following requirements:
Users must be able to sync offline versions of all files to local computers.
The organization must be able to manage permissions for all files.
You need to recommend a solution.
Which solution should you recommend?

A.
Microsoft Storage Spaces

B.
SharePoint document libraries

C.
Windows offline files

D.
Distributed File System Replication

Explanation:
You can work offline and sync within a SharePoint document library.
The document library permissions can be managed by the organization.
Incorrect answers:
Not A: Storage Spaces, a technology in Windows and Windows Server that enables you to virtualize storage by grouping industry-standard disks into storage pools.
Microsoft Storage Spaces is not used by Office 365.
How to work with Documents Offline in SharePoint 2013
http://www.learningsharepoint.com/2012/12/12/how-to-work-with-documents-offline-in-sharepoint-2013/