I think option D is the best choice. Providing the location and update instructions would be really helpful for users who need to fix the out-of-date issue.
Option C seems like the most useful information to include in the message. I want to know where I can get an updated virus-pattern file, not details about the old one.
Katina
17 minutes agoFrance
3 days agoMozell
4 days agoKizzy
5 days agoArlette
6 days agoRodrigo
7 days agoDahlia
8 days agoValentine
12 days ago