You just purchased a single license for the latest Microsoft Office Suite. Your friend has asked to borrow the CD, so he can install it on his computer, too. Is it okay for him to install it?

No; acts of piracy are legal; however, I paid for it. If he wants it, he can pay for it, too.
No; this would be considered piracy, so he should buy his own license.
Yes; I purchased the single license, so I can install it on as many computers as I want.
Yes; this would only be considered piracy if my friend paid me to install it on his computer too.