Which virus activates when a specific file type is executed?

The selection of a macro virus is accurate because this type of virus is specifically designed to exploit the capabilities of macro programming languages, typically found in applications like Microsoft Word or Excel. A macro virus activates when a document containing the malicious macro is opened, executing embedded code that can cause damage or compromise information.

Macro viruses take advantage of the fact that many users enable macros in documents without understanding the risks involved. When a macro-enabled file is executed, the code can run automatically, allowing the virus to proliferate, steal data, or perform other harmful actions. This form of virus is particularly prevalent in environments where productivity applications are used extensively.

In contrast, a boot sector virus impacts the boot process by residing on a computer's hard disk or removable media, executing when the system boots up. A program virus attaches itself to executable files and activates when those files are run, but it is not specifically tied to file types such as documents. A multipartite virus combines characteristics of multiple virus types, activating in various ways based on its design.

Thus, the macro virus stands out for its direct operation tied to executing specific file types, particularly within the context of office productivity software.