Final answer:
The best way to protect against virus attacks is to never open unknown e-mail attachments and to be cautious about the sources of attachments.
Step-by-step explanation:
The correct answer is D) never open unknown e-mail attachments.
Opening unknown e-mail attachments can introduce viruses into your computer and compromise your security. It's important to be cautious and only open attachments from trusted sources.
Other ways to protect against virus attacks include setting up a firewall, using encrypted transmissions, and using secure e-mail software. Additionally, using anti-virus software on your computer can help detect and remove viruses.