Which of the following virus is a script that attaches itself to a file or template?

A boot sector virus infects the master boot record or volume boot record of a storage device, not file templates or scripts.

A Trojan horse is malware disguised as legitimate software and does not attach itself to files or templates - it is a standalone deceptive program.

A macro virus is specifically a type of malicious script written in a macro language (such as VBA) that attaches itself to documents or templates like Microsoft Word or Excel files. When the infected file is opened, the macro executes automatically, allowing the virus to spread to other documents. This distinguishes it from other virus types by its reliance on application-level scripting rather than executable binaries.

An email virus spreads through email attachments or links but is defined by its propagation mechanism, not by attaching to templates or scripts specifically.