You are the Office 365 administrator for your company. All users have been assigned E3 licenses and use Office Web Apps

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You are the Office 365 administrator for your company. All users have been assigned E3 licenses and use Office Web Apps to create and edit documents.
A user attempts to access documents stored on a USB flash drive. When the user double-clicks a file that is stored on the USB flash drive, an error message states that Windows can't open the file and needs to know what program to use to open it.
You need to ensure that the user can start Office applications and edit Office documents by double-clicking files.
What should you do on the user's computer?

A. Use Office on Demand.
B. Install Office 365 ProPlus from the Office 365 portal.
C. Copy the files from the USB flash drive to the local hard drive.
D. Install and configure Microsoft Word Viewer.