Which of the following is a virus that combines both boot sector and program characteristics?

A multipartite virus is a type of malware that can infect both the boot sector of a disk and executable files. This dual capability allows it to spread in multiple ways: it can infect a system when the computer boots up, as well as during the execution of infected programs. By targeting both the master boot record (the area that loads the operating system) and specific application files, multipartite viruses can be more resilient and challenging to eliminate compared to viruses that specialize in only one of these infection vectors.

The other types of viruses mentioned serve different purposes. An encrypted virus is designed to hide its code by encrypting it, which complicates detection but does not specifically involve boot sectors or multiple infection strategies. A polymorphic virus changes its code every time it infects a new file to evade antivirus software but, like the encrypted virus, it doesn't specifically combine boot sector and program characteristics. A macro virus, on the other hand, typically infects documents and uses macros within applications like Microsoft Word or Excel; it is also not designed to infect the boot sector. Therefore, the multipartite virus stands out as the one that effectively incorporates both characteristics.