What does it mean if a virus is described as 'encrypted'?

Describing a virus as 'encrypted' means that the code of the virus has been altered to make it unreadable or disguised, often to evade detection by antivirus software and security tools. This encryption allows the virus to maintain its functionality while hiding its true nature from security measures. When a virus is encrypted, it can execute its malicious actions without being easily identified, increasing its chances of successful infiltration and spread within a system.

The other options do not accurately reflect the implications of a virus being encrypted. For example, an encrypted virus is not necessarily slowed down during execution, nor does encryption render it harmless or cause it to operate visibly. In fact, encryption serves the purpose of stealth, allowing the virus to execute its payload without drawing attention to itself.